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1 messages · Page 144 of 1

slim pawn
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because it is 10√2cm

granite light
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you can find that side too

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but actually no

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yes

slim pawn
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and the question is asking about 10√2cm

granite light
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it is 10√2

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coincidence

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it is asking to consider the case where container is full to the brim

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in other words the h√2 hypotenuse is equal to the segment you marked in purple

slim pawn
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in this case

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i gotcha now

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so it is 20√2 right?

granite light
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20/√2

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because h√2 = 20cm -> h = (20cm)/(√2)

slim pawn
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yes

granite light
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now this doesn't look like 10√2

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but actually

slim pawn
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do we have to rationalise?

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(20cm)/(√2)

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i think we do have

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because if we rationalize

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it will be 20√2 / 2

granite light
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you got it

slim pawn
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let's go

granite light
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well 20/2

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is 10

slim pawn
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yeah

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perfect

granite light
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so the other part asks you to find the volume

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which you can do by finding the area of rectangle+area of triangle and multiplying that by 10cm

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(because formula for the volume of a prism or something)

slim pawn
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idk how to proove it

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but i think the liquid will be the purple

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so

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the volume is 1000

granite light
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no the liquid is green

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the surface of the liquid has to be parallel to the ground

granite light
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because gravity

slim pawn
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10 * 10 * 10

granite light
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why?

slim pawn
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the yellow side is 10

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no

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it is 500

granite light
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why?

slim pawn
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we know that yellow, red and blue is 10

granite light
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do you mean area or volume?

slim pawn
granite light
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ok

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and we know angle between red and yellow is 90°

slim pawn
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yes

granite light
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if that wasn't the case we couldn't apply this formula

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so what about the rectangle

slim pawn
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we don't know the length of the missing side

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the height

granite light
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we know height + yellow = 20

slim pawn
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so the height would be 10

slim pawn
granite light
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no

slim pawn
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ok

granite light
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but we are saying it's full all the way for part b

slim pawn
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so the height is really 10

granite light
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yes

slim pawn
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so the volume is 1000

granite light
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yes, and then the total volume is

slim pawn
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the liquid?

granite light
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yes

slim pawn
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1000

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isnt it?

granite light
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no?

slim pawn
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1500

granite light
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why?

slim pawn
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1000 + 500

granite light
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yes

slim pawn
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no

granite light
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1500cm³

slim pawn
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the triangle is not like this anymore

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the triangle changed

granite light
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it actually didn't

slim pawn
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really?

granite light
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it just moved up

slim pawn
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no, in this case we added liquid

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because the rectangle in bigger and the triangle is the same

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so we have more liquid now

granite light
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yes

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but we calculated the volume for the big rectangle

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(rectangular prism, technically)

slim pawn
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i can see the answers too if you want

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but i think we didnt added liquid

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lemme see here

granite light
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1500cm³ is correct

slim pawn
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hmm

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you are right

granite light
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there is an easy way to see this actually

slim pawn
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tell me

granite light
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the total volume of 10x10x20 is what?

slim pawn
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2000

granite light
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we can split it into 2 equal cubes

slim pawn
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1000

granite light
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we can split each cube along the diagonal in half

slim pawn
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500

granite light
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split the top cube such that you remove the part which would overflow

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so you have 3/4 of the 2000

slim pawn
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1500

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that is weird

granite light
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that's the easy way to answer b

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but this methods doesn't work at all for c

slim pawn
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i think i understood now

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so it really added liquid

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i thought that we could move the arrow

granite light
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well the amount of liquid is determined by where the arrow points

slim pawn
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wait

granite light
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idk how to explain this better

slim pawn
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so the arrow continued in the same place?

granite light
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in the new diagram it points to the edge

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of the thing

slim pawn
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understand

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my biggest problem was probably because i didn't understand the question

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anyways

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thank you

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have a great day

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.close

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cobalt cloak
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how to show that there is instataneous acceleleraton at t = 10 given v=0.5t for 0≤t≤10, v=0.25t^2-8t+40 for 10≤t≤20

livid thunder
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find v at t=10 for both equations

cobalt cloak
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how do i justify it?

livid thunder
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well if its velocity gives different answers at t=10 then the only way for that to be true is if it accelerated instantly

cobalt cloak
livid thunder
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i mean u can if u want

cobalt cloak
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leaden nacelle
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you can draw it

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that proves that there is a vertical line in the velocity

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meaning instant acceleration from one velocity to another

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if that makes sense

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@cobalt cloak Has your question been resolved?

cobalt cloak
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😭

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i get what you mean

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wraith hinge
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hello

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wraith hinge
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i need help with calc 3 problem

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i solved a

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but i dont know how to solve b

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<@&286206848099549185>

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wraith hinge
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<@&286206848099549185>

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@wraith hinge Has your question been resolved?

unique minnow
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Well using the hint, can you give a vector from the equation of the plane that we know is always perpendicular to the plane?

wraith hinge
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well i can know the normal to the plane

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using the equation of it

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but idk what to do after that

unique minnow
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Well we would want a point on the sphere where the vector from the center of the sphere to that point is parallel to the normal vector.

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Can you give the center of the sphere?

wraith hinge
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yes u have it

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look i formed a line equations

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equation *

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using the normal vector as a direction vector

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and the center as a poin on it

unique minnow
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That's good.

wraith hinge
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then i used

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the parametric equation

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in the eq of the plane

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found t

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then found x y z

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does that work?

unique minnow
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Yeah that's fine.

wraith hinge
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very good

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thank u for ur help

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nova spire
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I don't understand what you mean by that

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and I'm not sure why 6*2 gives you the second digit

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sure last digit is 1

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but what you're doing isn't really justified

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@wraith hinge Has your question been resolved?

sudden mist
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Oh you could just do this with the binomial expansion

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idk if the video does that

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Maybe the method you did it in is a lot more effective, but i could do it by rewriting 61 as 6*10 + 1

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To find the last two digits

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we want to find the coef. a,b which are in the form a 10^1 + b 10^0

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the binomial expansion lets us do this

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by expanding the first two first of (6*10 + 1)^12

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we get the two terms ${12 \choose 0}(6\cdot 10)^0 + {12 \choose 1}(6\cdot 10)^1$

solid kilnBOT
sudden mist
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here the left term is just 1

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while the right term is 720

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so the first digit is 1

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and the 2nd is 2

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Since its the first two terms of the binomial expansion, and anything higher would be a bigger exponent in the (6*10) factor, thus a bigger digit and it does not contribute to the digits before it

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I.e you sum 1 and 720

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the one from above

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then read off the two first digits

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the 7 here is not correct for the third btw

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you need to calculate another term for that

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Remember what i wrote above

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To read off the digits, we want to find a way to express the number in the form ... + a 10^1 + b 10^0

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where a is the second digit and b the first

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we could do this via the binonal expansion

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But again, this might not be the best method

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Did you read the above?

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Go from the start and start there

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What is the second digit in 721?

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im only including the 7 here to show that this comes from the above calculation

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but its irrelevant here

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Where did you get?

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Oh i see you rewrote it

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Yeah so did you follow the part before it?

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This does not give the second digit in general btw

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yeah

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So let's go trhough the details again

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are you familar with the binomial expansion?

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Of the binomial expansion?

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uh idk expand (a+b)^n for fixed a,b and natural n

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youll have to know how to use the binomial expansion formula

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but idk if ur method requires that; so maybe useless to learn

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We'll need it for my method

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but thats assuming you want to understand it

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if not, thats perfectly fine

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Oh i just checked it and it seems theyre doing something very simliar with the binomial expansion

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but not rewriting 61 as 6*10 + 1

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in any case

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youll have to understand the binomial expansion formula if you want to understand why this works

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the binomial expansion formula?

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well it depends on what level, do you want to understand why its true or just see the formula?

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let's try

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i'll first just tex the formula and work from there

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Suppose $a,b$ are real numbers and $n$ is a natural number. Then we have that $(a+b)^n = {n\choose 0}a^0 b^{n-0} + \cdots + {n\choose n}a^n b^{n-n} $.

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This is the formula

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are you familiar with the notation used?

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Hm

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lets maybe try and rewrite it without sigma notation

solid kilnBOT
sudden mist
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Does this look more familiar?

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Uh thats fine, no worries

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This one ${n\choose k}$?

solid kilnBOT
sudden mist
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Are you famliar with factorial, like n! ?

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like combinatorics in general

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neat

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so are you aware of permutations?

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n! would be a kind pf permutation

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so we could permutate a subset of objects from a bag of things, say we want to permute 3 from 6 objects

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then we notice that in total theres 6! ways, but we have to divide away the number of way of not selecting 3 things, so (6-3)! number of things.

I.e the total number of ways to select 3 out of 6 objects (when order matters) is 6!/(6-3)! number of ways, so in notation that would be P(6,3). Again, in other words the number of permutations of 3 things out of 6

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Okay so the bracket notation is basically permuations but without order

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so ${n\choose k} = \frac{P(n,k)}{k!}$

solid kilnBOT
sudden mist
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there we go

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I.e this bracket notation is the total number of combinations

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Where the total number of permutations (from $k$ elements out of $n$) as we saw was just $P(n,k)=\frac{n!}{(n-k)!}$

solid kilnBOT
sudden mist
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Makes sense?

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yup!

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Why would you think that?

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0! is infact defined

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and its not zero

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Its defined as 1

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incase that was unclear

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In any case, hopefully that notation is clear

sudden mist
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I'll try explaining why this is true

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Sounds good?

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Let me also just repost the image for clarity

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Alright, so in order to get a term in (a+b)^n = (a+b)(a+b)....(a+b); then we must in each parenthesis choose either a or b.

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Right?

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Yeah but without order now, so the bracket notation

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Notice that the terms a^k b^n-k occurs as many times as we can choose a in k, out of the n parenthesis's, i.e exactly n choose k, (the bracket notation)

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So each term a^k b^n-k has a corresponding coefficient n choose k

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and thats pretty much it

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Yeah sorry i should of made that clear, here k is the term we're talking about, so k = 0 is the first term and k = n is the last term

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i could of added that back in again

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let me do that quickly

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Suppose $a,b$ are real numbers and $n$ is a natural number. Then we have that $$(a+b)^n = {n\choose 0}a^0 b^{n-0} + \cdots + {n\choose k}a^k b^{n-k} + \cdots + {n\choose n}a^n b^{n-n}. $$

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Looks rather messy though

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thats why i prefer the sigma sum notation for stuff like this

solid kilnBOT
sudden mist
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So first off a^k b^(n-k), do you understand this part?

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the terms

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Yeah

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do you understand how we got there from the line above?

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So think of it like this way, when you multiply each parenthesis, you naturally do so by distributing the a's and b's depending on which parenthesis youre working with, right?

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Say in the first parenthesis you picked a, then you have a binary choice what to multiply this with, either a or b in the next parenthesis.

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Suppose you only pick b afterwards

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then you get a term of the form a^1 b^(n-1), right?

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Now its just the n parenthesis from (a+b)^n = (a+b)(a+b)...(a+b)

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i.e the start

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Take (a+b)(a+b) for example, you could start from the left and say first pick a, and then multiply it with either a or b in the next parenthesis, right?

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so you either get a^2 or ab

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or in general, a^2 b^(2-2) or a^1 b^(2-1)

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right?

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Notice that this is just of the form a^k b^(n-k)

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im trying to rewrite it in the more general setting, therye the same still

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b^(2-2) = 1

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just to motivate where a^k b^(n-k) comes from

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its basically a sequence of yes and no's for selecting a or b in the multiplication

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Do you notice how when doing the multiplication for (a+b)(a+b)...(a+b) starting from the leftmost parenthis and going to each one to the right

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we're asking

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do you want to multiply a or b?

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Yes, but theyre seperate terms

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we want to get a hold of every term separately

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hence the formula above

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not to mention that some of these will occur more than others!

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for example

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a^n

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only occurs once

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and so does b^n

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and infact these are the only two terms in the expansion that occurs exactly once

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do you see how?

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Yup

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and why is that the only way to do so?

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notice how multiplication is commutative

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the order does not matter!

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while yes there are n! ways of multiplying all the a's

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it doesnt matter

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as all the a's are the same and multiplication commutes and we only pick a each time

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so we'll only get one such term

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so i guess this smoothly transitions to how we find how many times the other terms occurs, since you seem to agree that all the terms are of the from a^k b^(n-k) now?

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yeah

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so going back to (a+b)(a+b)

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notice how theres another way of getting ab

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by picking b instead at first

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and then a

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you're picking them from different parenthesis

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so the first ab was by multiplying the a from the first parenthesis, and the b from the 2nd. While the second ab we get by multiplying b from the first parenthesis (a different element, not the same as a) and then the a from the 2nd.

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Notice how these are genuinely two different ways of getting ab

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Comparing it to a^2, we can only do so once

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doesnt matter

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and the reason here is really because we're picking a and b differently in each parenthesis, thats why that counts as a different way

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youve already used up the a from the 1st parenthesis

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from the first ab

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if that makes sense!

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So this leads up the sentence "that the terms a^k b^n-k occurs as many times as we can choose a in k, out of the n parenthesis's, i.e exactly n choose k"

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We can make use of the notion of n choose k

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since this is what we're dealing with

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we're dealing with the amount of combinations, selecting an object out of a bigger collection, where order doesnt matter

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For example, how many ways are there of selecting a in 2 out the n parenthesis's?

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This hardly relates to it at this point in time

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but you need the formula for it

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which you said you didnt understand

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and wanted an explanation

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so heres my attempt of one!

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Well, its quite hard to go trhough a few weeks of combinatorics or whatever in just a few sentences, so if the explantion is not coming through its totally understandable; hopefully if you still care i think a video or two about the binomial expansion is better

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They might be more concrete

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Yeah i could tell, i feel mean for not stopping

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also its 4 am atm lmao

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I hope you got something out of this atleast

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hopefully it'll come easier when you decide to watch videos about it maybe

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or ask about it here

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maybe someone else can chime in, if u decide to keep the channel open

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The first part being?

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Oh i see

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well again, so what i was getting at before was that in either case youll need to be comfortable with the binomial expansion, in order for me to explain this

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since the method basically is just the binomial expansion

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he does every so slightly differently

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but it still uses that

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Yeah, im just using the formula is all

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And the fact that the formula writes it almost in the form a_1 10^0 + a_2 10^1 + ... etc

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so we can just read of the cofficents a_1, and a_2 to see what the first and 2nd digits are

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and since these are just the first two terms of the expansion this is rather easy

sudden mist
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but the person in the video does it slightly differently for some reason, using x instead of 10

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which is not clear why

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i alteast explain why that will work if i use 10, it makes sense atleast that way

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maybe the confusion here is that youre not aware what the purpose of rewriting the number as a_1 10^0 + a_2 10^1 + ... does?

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So you do get it?

sudden mist
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the rest is just the binomial formula

acoustic idol
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Too

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Yo

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Can anyone help me out with this question

sudden mist
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@wraith hinge Im gonna sleep now, so goodluck!

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ancient edge
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ancient edge
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My work to solve the SA however when I plugged in the values, I get differing answers

unique minnow
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I've not completely diagnosed it but the inside the of the square root should be 1 + 4u^2, not 1+2u^2.

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nimble grove
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nimble grove
nimble grove
# nimble grove

is there a way to simplify this before I make the limit goes to 0?

spiral kettle
# nimble grove

this step that you did to simplify the numerator was not valid in the first place (you can’t just bring the thing you’re multiplying by inside the tangent)

nimble grove
nimble grove
spiral kettle
# nimble grove Can i eliminate sin and tan before i put in y+5 to x?

that is certainly something that you can try. if you write tan as sin(the stuff inside)/cos(the stuff inside) you might end up with something that you can work with. also is this for a class or just standardized exam practice? if it’s just to prep for standardized exams then we can do some funny tricks

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arctic saddle
#

use the circle theorem to help find the values of the pronumerals (pls help thank you :))

worldly lagoon
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Isn't that 125

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115

arctic saddle
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HOW DID YOU GET THERE??

worldly lagoon
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The angle at the circumference is the half the angle at the diameter

arctic saddle
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Wow you're an actual wizard

arctic saddle
worldly lagoon
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Basically of there's a circle and an angle in the middle

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With straight lines to any point on the edge of the circle

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The angle formed by those lines will be 1/2 the angle in the middle

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Sorry I'm not too good at explaining things hope that helps

arctic saddle
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so does it matter if the straight lines are equal or does it just have to meet at the edge of the circle??

worldly lagoon
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Nope

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Just had to meet at the edge

arctic saddle
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OHHHHHH

worldly lagoon
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Basically try remember the shape in that question and if you ever see it again you know what to do

arctic saddle
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is the other lines for distraction btw??

worldly lagoon
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The other line also has the angle 115

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Cause it's the same shape

arctic saddle
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ohhhh okayy

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tysm man!!

worldly lagoon
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You're welcome

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arctic saddle
#

Sorry to ask another question but how do I prove that these triangles are similar?

arctic saddle
#

This one too sorry

supple saffron
#

,rotate

solid kilnBOT
prisma stone
#

just place the angles

supple saffron
supple saffron
arctic saddle
#

Ya not very good at trig sorry 😭

prisma stone
#

they don't have to'

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35+55 = 90
180 - 90 = 90

supple saffron
supple saffron
arctic saddle
#

Yes

supple saffron
arctic saddle
#

Oohhh

supple saffron
arctic saddle
#

How do I do that?? Sorry

supple saffron
#

so see triangle ABD and DBC

#

are they similar?

#

if yes show me

arctic saddle
#

Yes because we use AAA

#

BAE = CAD

supple saffron
#

we use sides for congruent which the triangle the same

arctic saddle
#

Ohh

supple saffron
#

now with that u can do this

arctic saddle
#

AAA

supple saffron
#

$\frac{BD}{BC} = \frac{AB}{BD}$

solid kilnBOT
supple saffron
#

plug every value

#

you got

#

$\frac{10}{7} = \frac{x}{10}$

solid kilnBOT
supple saffron
#

$x = \frac{10 \times 10}{7}$

solid kilnBOT
supple saffron
#

@arctic saddle here you go

arctic saddle
#

OHHHH

arctic saddle
supple saffron
arctic saddle
#

Using that how do I figure out x?

supple saffron
arctic saddle
#

I don't think so

#

But it might be on the test and I couldn't find any info on how to do it in the power points 😭😭

#

Is it the same as ratio??

arctic saddle
arctic saddle
sage jacinth
arctic saddle
#

Basically I have to prove similarity and find x

#

I know how to prove it's similar but idk how to find x

supple saffron
arctic saddle
supple saffron
sage jacinth
arctic saddle
#

So how do I find x??

sage jacinth
arctic saddle
#

Ohhh I seee

#

So if I get the ratio

sage jacinth
arctic saddle
#

3/8=2.67

#

That's the ratio

supple saffron
arctic saddle
#

Is that not right?? 😭😭

supple saffron
#

$\frac{10-x}{10} = \frac{3}{8}$

solid kilnBOT
sage jacinth
#

Solve
(10-x)/10 =(3/8)
& Calc x

supple saffron
#

use the method to multiply diagnoally idk what the name my english bad

arctic saddle
#

Ohhh

sage jacinth
arctic saddle
#

Wait how would you do it??

supple saffron
#

it is 8/3

#

,calc 3/8

solid kilnBOT
#

Result:

0.375
supple saffron
#

but it is useless

sage jacinth
#

@arctic saddle i think you first need to study some properties of similar triangle

arctic saddle
#

Okk

sage jacinth
#

Your profile animation is good and unique

#

I like that

arctic saddle
#

Thank you I brainrot on val

supple saffron
#

bro my pfp is empty idh any money i am broke

arctic saddle
#

Mines free

supple saffron
#

😭

supple saffron
arctic saddle
#

It's from a quest my guy!!

sage jacinth
sage jacinth
arctic saddle
#

I think all I did was join call and it gave me a quest

#

And then I accept it and just had to run val till it reach 100%

sage jacinth
#

I don't know much about this😅

arctic saddle
#

At least yk math

#

Which is more useful

sage jacinth
#

Know a little bit

arctic saddle
#

More than me lmaoo

sage jacinth
#

@arctic saddle u are most useful as u r edible, mushroom 🍄😉

supple saffron
#

math is to complex to know perhaps

arctic saddle
sage jacinth
#

Friends

arctic saddle
supple saffron
#

i am still grad 9bleakkekw

sage jacinth
#

Trigonometry is easiest,i think

arctic saddle
#

WHAT COUNTRY

#

THIS IS YR 10 EXTENTION

supple saffron
arctic saddle
#

WHAT

supple saffron
#

but since it math comp i haven't study trig

arctic saddle
#

That's actually insane 😭😭

sage jacinth
supple saffron
arctic saddle
#

I thought y'all were in uni or sum😭😭

sage jacinth
arctic saddle
#

Idk man y'all are just smart like that 😭

sage jacinth
#

As u r mashroom

arctic saddle
#

Insane

#

Also off topic but do you guys have tips on what to put on a maths notes page??

supple saffron
sage jacinth
arctic saddle
#

Byee

arctic saddle
supple saffron
sage jacinth
arctic saddle
arctic saddle
#

Calculator section

#

We're not learning calculas yet

supple saffron
arctic saddle
#

Should I put examples to help me??

sage jacinth
#

Yes

arctic saddle
#

okii thanks guyss

supple saffron
supple saffron
arctic saddle
#

yup

#

thank you for the help

#

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#
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vernal fern
#

how can i find the exact value of sin(-165)?

vernal fern
#

i need to use one of those half angle identities right

split chasm
#

not necessarily

#

you could so stuff like compound angle identities and oddness

cold dune
vernal fern
#

why?

split chasm
#

you could so stuff like compound angle identities and oddness
(and supplementary identity)

#

its more convenient than the half angle identity which gets you nested roots in many cases

cold dune
# vernal fern why?

for why sin(-165) = -sin(15) you can use the unit circle, or prove it like this:
sin(-165) = -sin(165) = -sin(180-15) = -sin(15)

vernal fern
#

first thing I have to do to solve for sin(-165)

cold dune
cold dune
#

let's do that step by step

vernal fern
#

okay

cold dune
#

you have sin(-165)

#

do you agree that it's equal to -sin(165)

vernal fern
#

yes

cold dune
#

alright, so we have -sin(165) = -sin(180-15)

#

this is where we can use supplementary angle identities

#

do u know them?

vernal fern
#

um

#

no

cold dune
#

ahh i see
so there are a couple identities which you can use when you have sin(180±x) or cos(180±x), to make them simpler, the one you're gonna use here is
sin(180-x) = sin(x)

#

you can prove it just by doing that on the unit circle

#

the other ones are
cos(-x) = cos(x)
cos(180-x) = -cos(x)
cos(180+x) = -cos(x)
sin(180-x) = sin(x)
sin(180+x) = -sin(x)

cold dune
vernal fern
#

wait so decimal form -0.99

cold dune
#

we're still dealing with angles though

#

where'd you get -0.99 from?

vernal fern
#

i just used a calculator to check

cold dune
#

oh

#

I meant try using the identity to change -sin(180-15)

#

we'll get to the exact value in a bit

vernal fern
#

oh wait you did

#

which identity though?

cold dune
#

sin(180-x) = sin(x)

#

try using this^ to change -sin(180-x)

vernal fern
#

im so sorry i dont understand

cold dune
#

it's ok let's break it down

#

you know the unit circle though right?

vernal fern
#

yes yes i do

#

love the unit circle

cold dune
#

frr

#

ok so

#

imagine you start from 0 on the unit circle, and move an imaginary amount, say x degrees on it

vernal fern
#

yes alright

cold dune
#

it'll look like something like this

cold dune
#

now about the point on the circle we're pointing at, do we agree that it's y coordinate is equal to sin(x)?

cold dune
#

for example if we move 30 degrees on the circle, we'll get to a point where its y coordinate is sin(30), or 1/2 to be exact

cold dune
#

now imagine if we start from 0, then move 180 degrees on the circle, and then move back x degrees

#

something like this

#

we see that if we move x degrees or 180-x degrees on the circle, we get the same y coordinate (in other words, we get the same sine)

vernal fern
#

wait why are we doing that though

cold dune
#

that proves sin(180-x) = sin(x)

#

so in your question we have -sin(180-15)

#

following the same logic, we can say -sin(180-15) = -sin(15)

vernal fern
#

oh

#

so we move the thing that isnt sine to get the same sine?

cold dune
#

all we did was change sin(-165) to -sin(15), to make it simpler to solve the problem

#

do you know about compound angle identities though?

vernal fern
#

also no

#

but i have google!

cold dune
#

nice!

#

in short

#

sin(x+y) = sin(x).cos(y) + sin(y).cos(x)
cos(x+y) = cos(x).cos(y) - sin(x).sin(y)

#

as u can see, we can write -sin(15) as -sin(45-30)

vernal fern
#

oh oh oh

cold dune
vernal fern
#

okay thank you very much i have to run to work i will do this on my break and come back in a couple hours

#

thank you very much!!!

cold dune
#

cheers! good luck

vernal fern
#

so sorry i cant see it thru rn time management where

#

.close

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#
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drifting storm
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drifting storm
#

guys can anyone pls help guide on how to solve this

lilac flame
#

you can start by simplifying what's inside the modulus

drifting storm
#

i tried this way but i think it’s wrong

drifting storm
lilac flame
#

yes

#

commond denominator

drifting storm
#

oooh

lilac flame
#

you should plug in the solutions you found

#

to check if they're correct

#

because for example the left side is only true if what's inside the modulus is positive

drifting storm
#

ooohhhh

#

ohhhh ure rightt

#

i got it correct alreadyy

#

thank you so muchh

#

.close

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lilac flame
#

np

drifting storm
#

.reopen

trim joltBOT
#

drifting storm
#

btw guys, is |21/5| = -21/5?

nova spire
#

no

#

|21/5| is 21/5

#

since 21/5 > 0

#

|x| always outputs the positive (non-negative) value

drifting storm
#

ohhh wait yes ure right, absolute value should give non negative results

#

so do i conclude that this equation only has one solution?

drifting turtle
#

solve 2x+7 = 0 first to note when the absolute value function changes the sign of 3x

#

which is -7/2

#

now for each case x >= -7/2 and x < -7/2

#

for the first case the RHS is just 3x, for second case RHS is -3x

#

then solve for each case

#

reject when the answer contradicts the assumption (for the first case l, x>= -7/2)

drifting storm
#

ooohh okk thanksss

#

.close

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#
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drifting turtle
#

np

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trim joltBOT
prime lynx
#

Yeah sure

nimble stone
#

i would say or rather than and, but sure, both are okay

prime lynx
#

Although change the and to or

nimble stone
#

and means it has to satisfy both of them to use that expression

#

which doesnt work

#

or means it can satisfy either or both

#

that much is fine, yeah

#

no real difference really, one just takes less time to write

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untold phoenix
#

Hey I need help with this

trim joltBOT
untold phoenix
#

This is the drawing I’ve setup

#

Now Im a little confused with finding the top of my Z, because Z = to squareroot of 9-y^2 seems right

#

But the thing is why is that the case? Its a cylinder extending infinitely into X no?

prime sierra
#

the plane y=3x prevents x from getting to infinity.

#

and y is limited to 0<=y<=3

untold phoenix
#

That black shape is my new drawing, that’s the solid right?

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#

@untold phoenix Has your question been resolved?

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deep solstice
#

if 100% is 124
.... %? 279

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pseudo zodiac
pseudo zodiac
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#

@deep solstice Has your question been resolved?

#
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snow night
#

I need help

trim joltBOT
snow night
#

A guy asked 50 dollars from his mom and dad so he could buy a shirt, he now has 100 dollars. He then went outside to buy a shirt, he said "Hey, how much is shirt?" The seller said "100 dollars" he then said "can I get a discount?" The seller "said sure I'll sell it to you for 97$" he now has 3 dollars that he will give it to both his parent's and the extra 1 dollar for him. He then gave 1 dollar to both his parents, since he gave the 1 dollar back the parents gave him 50 each in total. 49+49 = 98$ + 1 from his extra change = 99$. Where did the extra 1 go$

solid kilnBOT
#

𝗖𝗼𝗿𝗺𝗮𝗰

empty sluice
#

Wait. If he gives 1 dollar each to his parents, he has 1 dollar with him. Then his parents give him 50 each. So won't he have 1+50+50=101? Or did I get the question wrong?

snow night
#

Then he bought shirt for 97

#

He now has 3

#

He gave 1 dollar to his mom and dad

#

He kept 1 dollar

empty sluice
#

Right

snow night
#

Then

#

Since he gave 1 to his parents

#

The parents made 1 dollar

#

So like

#

Wait

#

It's like this

empty sluice
#

They don't give him 49, they give him 50

#

!original

trim joltBOT
#

Please show the original problem, exactly as it was stated to you, with the entire original context. A picture or screenshot is best. If the original problem is not in English, then post it anyway! The additional context might still be helpful. Do your best to provide a translation.

snow night
#

It was just told

trim joltBOT
#

@snow night Has your question been resolved?

wind cloak
# snow night It was just told

So after he gave 1 dollar to each of his parents, we can see this new situation like the both the parents gave him 49 dollars each.
So he has total 98 dollars. From these 98 dollars, he bought a shirt for 97 dollars and kept one for himself

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#
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#
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strange imp
#

In the following system of equations, y can be expressed as m/n, where m and n are positive integers and relatively prime. What is the value of m + n?

strange imp
#

(A)30 B(14) C(27) D(12) E(24)

#

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static girder
#

Javier draws a quadrilateral. The first and second angles are equal. The third angle is 45° more than the first angle. The fourth angle is half the size of the first angle.

(a) Let the size of the first angle be x. Write down the sizes of the other three angles in terms of x.

(b) Form an equation in x and solve for y x to find the size of each angle of the quadrilateral.

I have done a which is
1, 2 = x
3 = x + 45°
4 = x ÷ 2.

I'm still stuck on b because I don't know what equation to make.

mild oxide
#

Yo

static girder
#

Hi

mild oxide
#

1st is x and 2nd is x 3rd is x+45 and 4th is x/2

#

Fr

static girder
#

Yes I've done that

mild oxide
#

Now see

#

Do u know sum of all angles of quadrilateral is 360 degree

#

Enjoy

static girder
#

Ok ty, I'll see what I can do

#

How do I close this

mild oxide
#

.close

static girder
#

ok tysm

#

.close

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#
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mild oxide
#

Welcome

trim joltBOT
#
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lavish sequoia
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hollow arrow
#

quadratic equation?

lavish sequoia
#

Yh

#

I put 2.

#

Which is wrong

hollow arrow
#

Isn't it supposed to be 0?

lavish sequoia
hollow arrow
#

the discriminant is less than 0

lavish sequoia
#

yh

hollow arrow
#

So there are no real solutions

lavish sequoia
#

oh

#

okay

#

tyyyy

hollow arrow
#

if the discriminant = 0

lavish sequoia
#

yep

hollow arrow
#

then there is one real solution

lavish sequoia
#

yh

hollow arrow
#

Okay I think you got it

lavish sequoia
#

thnx

lavish sequoia
hollow arrow
#

np

lavish sequoia
#

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trim joltBOT
empty sluice
#

What are you supposed to find?

supple copper
#

i mean

#

i just guessed

vernal briar
#

Yeah guessing is easy here

supple copper
#

pick 3 integers that multiply to 4

elder glade
#

I know but how do u do it with equations

supple copper
#

you don't

#

maybe you do actually im not sure

#

there's some weird cubic factorisation methods i've not studied

#

in general it's really ass though

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#
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#

supple copper
#

i wouldn't

#

i just said, i wouldn't

#

i'd look at it

#

try to guess

#

if it doesn't work i'd give up

#

lol

#

i mean i suppose you can substitute things in and see if it works

#

solve for alpha, sub into beta, etc etc

#

that's a pain though

#

idk it sounds terribel

#

there's a cubic formula if you want to take a look

#

no one really uses it though

sudden mist
#

IIRC you could also try to exploit some kind of symmetry to avoid solving a cubic

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#
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fathom flicker
#

Is the answer of question 17 D?

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fathom flicker
#

.close

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steady silo
#

hhelpme

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pale tulip
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pale tulip
#

I had a attempt at the question

#

not sure how I’m doing

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#

@pale tulip Has your question been resolved?

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marsh forum
#

Can I have this verified

trim joltBOT
marsh forum
#

I can tex it if required

grim sparrow
#

do you mind elaborating a bit when you say “by definition”?

chilly bobcat
#

you can start with calling a variable x, where x belongs to A

worldly wing
#

What does U_f represent?

chilly bobcat
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all the elements in the family of sets F

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if F is {{1, 2}, {2, 3}} then U F is {1, 2, 3}

worldly wing
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How is it different than F itself then

worldly wing
sudden mist
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It’s just the union

worldly wing
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Oh then it’s just the union of all the sets in F

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Yeah

sudden mist
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It has a precise definition in this case, which the exercise is all about

marsh forum
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One minute, have some bank work to finish, will be back in 5

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So I basically have to define the unions of multiple sets here

sudden mist
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You have to define? Isn’t it already given

marsh forum
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It is

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So what do I even write then

sudden mist
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Try and unpack what you have and what the goal is

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For example unpack what it means for a set to be a subset of another, since after all this is what you’ll need to show

marsh forum
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$x \in A_i$

solid kilnBOT
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ƒ(Why am. I here)=I don't Know

sudden mist
marsh forum
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One minute

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Trying to construct the definition of union

sudden mist
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Why are you constructing it? It should already be given

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In your textbook or whatever it may be

chilly bobcat
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i dont know if there's any special theorem to make it clearer so this is the best I can do

sudden mist
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??

chilly bobcat
sudden mist
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A subset U F is what we want to show

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This looks confusing

chilly bobcat
chilly bobcat
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im trying to make sense of it too

sudden mist
chilly bobcat
marsh forum
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So my proof is wrong?

solid kilnBOT
chilly bobcat
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better now?

sudden mist
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I mean in any case I don’t see how this is helping

sudden mist
chilly bobcat
marsh forum
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So I need to write the definition of union essentially right?

sudden mist
sudden mist
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First off start slow

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You’re essentially showing a set is a subset of another set

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What does that mean? Start like that and peel the layers slowly

chilly bobcat
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that's essentially what it means

sudden mist
chilly bobcat
marsh forum
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So this essentially means that $x \in A \implies x \in B$

chilly bobcat
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I've never done questions using UF

chilly bobcat
sudden mist
solid kilnBOT
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ƒ(Why am. I here)=I don't Know

sudden mist
#

And in our case B is?

marsh forum
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so F

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wait

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UF

sudden mist
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Yeah

marsh forum
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$\bigcup F$

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sorry

solid kilnBOT
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ƒ(Why am. I here)=I don't Know

sudden mist
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So in your textbook, do you have a definition for a union over a family of sets?

marsh forum
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so as every arbitrary element x that belongs to A belongs to $\bigcup F$ we have that $ A \subseteq \bigcup F$

solid kilnBOT
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ƒ(Why am. I here)=I don't Know

sudden mist
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That’s what we’re trying to convince ourselves of in the moment yes

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But we haven’t shown it yet

marsh forum
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what do you mean

sudden mist
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We want to show that A is a subset of union F

marsh forum
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yes

sudden mist
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It doesn’t mean it’s necessarily true

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So convince me!

marsh forum
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so you want me to define union now right?

sudden mist
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I could do it for you, the reason we need to is to unpack what the notation is saying; or else it could really mean anything

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So x is an element of union F iff there exists some element B in F such that x is an element of B

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Does your textbook state something similar?

marsh forum
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for union my book defined it as follows

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$A \cup B = {x| x \in A or x \in B }$

solid kilnBOT
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ƒ(Why am. I here)=I don't Know

sudden mist
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That’s a union between two sets, we’re talking about over a family of sets

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Is there one for a family of sets?

marsh forum
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let me check

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$\bigcup F = {x | \exists A \in F(x \in A)}$

solid kilnBOT
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ƒ(Why am. I here)=I don't Know

sudden mist
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Yup this is the exact same

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Note that the letter A here isn’t necessarily the same set so it’s best to use a different letter like I did

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So if we pick an element in the union it satisfies the latter condition which you have written

marsh forum
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hmm, yeah

sudden mist
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But notice that by assumption we have that x is in A

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so there does indeed exist an element in F (pick B=A)

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Such that x is in B

marsh forum
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oh , that's it?

sudden mist
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Yup!

marsh forum
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wow

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thanks

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I've really got to learn to use defns

sudden mist
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Np happy

marsh forum
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I'm used to using intutution

sudden mist
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Yeah that’s what I realized too

marsh forum
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sadge

sudden mist
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Definitions are really important

marsh forum
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yeah, thanks

sudden mist
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Use intuition to make a strategy

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But use definitions to actually prove it

marsh forum
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got it

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thanks

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.close

trim joltBOT
#
Channel closed

Closed by @marsh forum

Use .reopen if this was a mistake.

trim joltBOT
#
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spring bolt
#

If four sides of parallelogram sides touches a circle like this then it will be

spring bolt
#

Square?

trim joltBOT
#

@spring bolt Has your question been resolved?