#help-0

1 messages · Page 319 of 1

cold pumice
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Wait

sterile hill
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Mhm plug in infinity

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And then simplify

cold pumice
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Why is this legal? I mean dividing each number inside the root

vale wigeon
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$\sqrt{ab} = \sqrt{a} \sqrt{b}$

ocean sealBOT
sterile hill
#

You’re force factoring^

vale wigeon
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and since x is positive, 1/x = sqrt(1/x^2)

cold pumice
cold pumice
cold pumice
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@vale wigeon Why this is not what you get

vale wigeon
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$\frac{1}{x} \sqrt{x^2 - 3x} = \sqrt{\frac{x^2-3x}{x^2}}$

ocean sealBOT
vale wigeon
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thats what im doing here

sterile hill
cold pumice
#

Oh wait

sterile hill
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Square root of x^2 = |x|

sterile hill
cold pumice
cold pumice
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So the limit I get is -4 right?

sterile hill
vale wigeon
sterile hill
sterile hill
cold pumice
#

Ok wow thanks @vale wigeon !
A very neat trick, I will try to remember it

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lone heartBOT
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cold pumice
#

.reopen

lone heartBOT
#

cold pumice
vale wigeon
#

indeed, in that case 1/x will be **-**sqrt(1/x^2).

cold pumice
#

righttttt

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Sorry my brain is not braining

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Again tysm

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timber cobalt
#

I'm trying to find out the formula for the volume of a cone.

If we consider all the right triangles (with their heights being the height of the cone) constituting a cone, we might see that, just like it is with all the right triangles, they take up exactly half the area of the rectangle with the same height and base length.

So, obviously, the cone has to have half the volume of the cylinder with the same base radius and height. To make it more obvious, we might replace the missing half of the rectangle by the triangle located symmetrically to the considered triangle relative to the height of the cone. Then we will visually have exactly half of the cylinder.

But it's a known fact that the volume of a cone is exactly a third of the volume of a cylinder with the same height and base radius. What mistakes did I make while trying to get the formula myself?

vale wigeon
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well intuitively

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if you think about triangles all attached to the cone's axis, it is like they cover space "denser" the closer you get to the axis

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like imagine them as made of paper or something

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they're closer together near the center than further out

timber cobalt
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Yeah, tho I am not sure it's applicable in math

vale wigeon
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it's my attempt at explaining intuitively why the area ratio does not translate into the same volume ratio

timber cobalt
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I understand your intention but am thinking over the explanation atm

vale wigeon
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also for the record, i don't know of any good visual that'd illustrate how 3 cones come together into a cylinder.

timber cobalt
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Why are you saying it?

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Oh, I got it

timber cobalt
vale wigeon
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reasonably so.

timber cobalt
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Just sending a message so the bot doesn't think I'm away.

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So however many triangles we take we won't have as many triangles / unit of space on the outskirts

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So if we take the space at the center as the required planes density for counting space as volume, we won't be able to call anything farther from the center volume because it doesn't have sufficient planes density

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Do you like my explanation?

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Tho I think such a miscalculation should make volume even lower than 1/3. Why did it suddenly become 1/2?

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I guess it's just because the method of calculation is inappropriate. For example we can take the outskirts as density standard. Also in most places there won't be space and just close triangles or the planes density will be too high depending on what density standard we choose.

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I appreciate your help but I wouldn't be able to understand the answer without this page https://math.stackexchange.com/questions/4632714/why-is-the-volume-of-a-cone-not-half-the-volume-of-the-cylinder-of-which-it-is-a and if I didn't recently teach a person what area and volume are

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void torrent
#

Hey, can someone tell me how to use a surface integral to get the volume of a cone?

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@void torrent Has your question been resolved?

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feral blade
#

in terms of the family of lines, (k-method), why is k undefined when m = 1/2

vale wigeon
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"k-method"?

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you may want to enlighten us on that.

feral blade
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family equation using k-method straight lines, the q for the proof says, prove that the equation of any line through the point of intersection P of two lines l1 : a1x+b1y+c1=0 and l2: a2x+b2y+c2=0 has the form l : (a1x+b1y+c1)+k(a2x+b2y+c2)=0 where k is a constant

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<@&286206848099549185>

vale wigeon
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don't quite see where m=1/2 would pop up here honestly

feral blade
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idk, it just says its undefined so i was just curious as to why

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remote pelican
lone heartBOT
remote pelican
#

I am now in

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then how? hellpp

unkempt vapor
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squares difference

remote pelican
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how

subtle birch
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1=1^2

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a^2-b^2=(a+b)(a-b)

unkempt vapor
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(20092007-1)(20092007+1)+(20092009-1)(20092009+1)

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there are 2 20092008

subtle birch
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well, don't just give out the solution

unkempt vapor
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which cancel out

remote pelican
unkempt vapor
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yes

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try it

remote pelican
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i dont really understand

unkempt vapor
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that's an equation

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which works

remote pelican
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ya what is a and b arent they both same?

tardy tapir
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a and b are arbitary constants

unkempt vapor
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a and b are just notations for numbers

tardy tapir
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they can take any values

unkempt vapor
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in this case 20092007 and 1

remote pelican
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ohhhh!

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I know alr

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but

unkempt vapor
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umm

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what about the top part?

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by canceling, i meant in both sides

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top and bottom

remote pelican
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then just left 20092006 + 20092010 ?

unkempt vapor
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yes

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but bottom part differs

remote pelican
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but the answer say 1 over 2

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why?

unkempt vapor
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as i said

tardy tapir
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the numerator isnt squared

unkempt vapor
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oh

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top

tardy tapir
unkempt vapor
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it is 20092008/(20092006+20092010)

tardy tapir
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just add the denominator now

remote pelican
#

40184016

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omg!

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thank a lot

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really thank you

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.close

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clear comet
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Why isn't this true?

lone heartBOT
unkempt vapor
#

well

vale wigeon
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hold on

unkempt vapor
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expanding brackets

vale wigeon
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it looks true unless you make some kind of typo

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who is saying it isnt true

echo socket
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,w is (sqrt(sqrt(41) - sqrt(5)) - sqrt(sqrt(41) + sqrt(5)))^2 = sqrt(41) - sqrt(5) - 2(sqrt(sqrt(41) - sqrt(5)) * sqrt(sqrt(41) + sqrt(5))) + sqrt(41) + sqrt(5)

unkempt vapor
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i see no error

sour dove
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Yeah same

vale wigeon
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,calc (sqrt(sqrt(41) - sqrt(5)) - sqrt(sqrt(41) + sqrt(5)))^2 - (sqrt(41) - sqrt(5) - 2(sqrt(sqrt(41) - sqrt(5)) * sqrt(sqrt(41) + sqrt(5))) + sqrt(41) + sqrt(5))

ocean sealBOT
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Result:

-1.4432899320127e-15
vale wigeon
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0

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close enough

unkempt vapor
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mb cause absolute value?

clear comet
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1 sec

vale wigeon
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@clear comet yeah, again, who is saying it is not true?

unkempt vapor
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yeah, it looks correct

clear comet
gleaming fjord
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oh

vale wigeon
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please open your own channel.

gleaming fjord
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mky bad

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my bad

past raven
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) How can you add a 5N and 4 N forces acting simultaneously on a body to produce a resultant of 7 N force?

unkempt vapor
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sqrt((sqrt(41)-sqrt(5))*(sqrt(5)+sqrt(41))) = 6?

vale wigeon
echo socket
vale wigeon
echo socket
#

Again, it is nowhere implied that those two are different

vale wigeon
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it is not actually claiming the two are different.

unkempt vapor
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,w sqrt((sqrt(41)-sqrt(5))*(sqrt(5)+sqrt(41)))

unkempt vapor
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they are same

clear comet
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so wa just doesnt simplify it to the same thing

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okay then

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Thanks

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.close

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cloud scaffold
#

how should i approach solving this?

lone heartBOT
cloud scaffold
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i have no idea where to begin

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( repost b/c of trolls in my help closed out the other one already )

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<@&286206848099549185>

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( time from previous help allots for ping sorry 🙇

lone heartBOT
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@cloud scaffold Has your question been resolved?

exotic belfry
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just try some selected values. for example: use t = 0 for (a) to (f), calc the points (x,y,z) and look which graph possible matches.

cloud scaffold
#

ah you're right

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ok thank you! @exotic belfry

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.close

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reef flame
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reef flame
#

Question 3 how do you determine the order 1,2,3 like how do you know

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<@&286206848099549185>

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agile wind
#

!status

lone heartBOT
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What step are you on?
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2. I have begun but got stuck midway
3. I got an answer but I'm told it's wrong
4. I got an answer and would like my work checked
5. I have a question about someone else's worked solution
6. None of the above
reef flame
#

I got the zeros: 3,-2 and 3/4 but idk how to indicate whether they are order 1,2 or 3

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And idk how to determine how to solve algebraically if each function is even or odd.

agile wind
#

u need to replace x by -x

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in f(x)

reef flame
#

So how would I do that

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plush pivot
lone heartBOT
plush pivot
#

Hello! I am looking to find a formula that can obtain the distance of a line originating from a point in space to any point on an XY plane below it. I will be provided the point of origin as well as the direction vector from that point of origin. The final result needs to be the length of the line segment that starts at Point P, travels in direction D, and ends at the XY plane some distance below the point.

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This is a 3D equivalent of the more simple "SOH CAH TOA" style problems. I just don't know exactly how it might work in 3D

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undone oar
#

Hi i am stuck here with a expression unknown from formula (sorry if badly translated) i would like a simple explenation

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undone oar
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.close

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sage hedge
lone heartBOT
sage hedge
#

I did the first part but for some rason I kept messing up the second aprt

tacit arch
#

!show

lone heartBOT
#

Show your work, and if possible, explain where you are stuck.

sage hedge
#

k one sec

alpine sable
#

$(b)$ is the exact same as $(a)$ just with a different $\epsilon$

ocean sealBOT
#

Replaced by new brandon H

sage hedge
#

like the arithmatic

alpine sable
#

look at what you did with a

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and change one number

sage hedge
#

is it 1.05647

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I just used desmos and used the quadritic formula

tacit arch
#

can you show your entire work

sage hedge
#

😏

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one sec

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20 - 0.005 = 19.995

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19.995 = x^2 - x

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0 = x^2 - x - 19.995

alpine sable
#

btw

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you wont have to use the quadraic formula if you just complete the square

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Also learning how to use latex would be great

sage hedge
#

what is latex

alpine sable
#

$|f(x)- L| < \epsilon$

ocean sealBOT
#

Replaced by new brandon H

sage hedge
#

how to complete square I haven't taken a math

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in like 2 years

alpine sable
#

$ax^2+bx+c =0$

ocean sealBOT
#

Replaced by new brandon H

sage hedge
#

oh

alpine sable
#

move the c to the other side

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$$ax^2+bx=-c$$

ocean sealBOT
#

Replaced by new brandon H

alpine sable
#

replace the left with $$(x-\frac{1}{2}b)^2$$

ocean sealBOT
#

Replaced by new brandon H

alpine sable
#

add $\frac{1}{4}b^2$ to the right side

ocean sealBOT
#

Replaced by new brandon H

alpine sable
#

so

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$(x-\frac{1}{2}b)^2 = \frac{1}{4}b^2-c$

ocean sealBOT
#

Replaced by new brandon H

alpine sable
#

then you can solve for x

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$x-\frac{1}{2}b = \pm \sqrt{\frac{1}{4}b^2-c}$

ocean sealBOT
#

Replaced by new brandon H

alpine sable
#

$x = \frac{1}{2}b \pm \sqrt{\frac{1}{4}b^2-c}$

ocean sealBOT
#

Replaced by new brandon H

alpine sable
#

this only works if a is 1 tho

sage hedge
#

bruh

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im lost in the sauce

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I need to go to school I have to work on this later, thanks for the help tho.

lone heartBOT
#

@sage hedge Has your question been resolved?

lone heartBOT
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indigo storm
lone heartBOT
indigo storm
#

I wanna solve x

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Tenth one

alpine sable
#

X?

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Oh tenth

indigo storm
#

yup

tacit arch
#

use pythagoran theorem and write it interms of just cosine or sine

charred summit
#

Tenth ?

indigo storm
#

yup

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10

tacit arch
#

$\cos^2(\th) + \sin^2(\th) =1$

ocean sealBOT
#

riemann

charred summit
#

Oh

tacit arch
#

then factor or quadratic formula from there

alpine sable
#

Then sin²x + cos²x = 1

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Then its a quadratic for sinx

indigo storm
#

this is what I did

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what can i do next?

indigo storm
#

cannot factor

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how to factor it?

near apex
#

Try checking if it's even factorisable.

tacit arch
#

,w factor 2x^2 + 3x + 2

tacit arch
#

nope

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so use quadratic formula

near apex
#

They probably need real values so no point.

indigo storm
#

will I be able to get general solutions

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between 0 and 2pi

near apex
#

There aren't any solutions. At least not for real angles.

indigo storm
#

wait but that questions asks for solutions

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let me send full

near apex
#

Well, then question is probably misprinted.

indigo storm
#

okkk

indigo storm
near apex
#

Well, make everything into terms of cos(theta) and then solve the polynomial, i suppose.

indigo storm
#

did u try?

near apex
#

I am not certain if there is a simpler way.

near apex
#

But i can see that it's going to a quartic. We know one root.

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So that gives us cubic.

indigo storm
#

yes

near apex
#

After that, rational root theorem, i think.

indigo storm
#

idk rational root theorem

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I should ask from the teacher

near apex
#

Do you know how to factorise a cubic?

indigo storm
#

yes

near apex
#

If yes, then you know what it is - you just don't know the name.

indigo storm
#

addition and difference between 2 cubes

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I know that

near apex
#

Oh. You mean like, a^3 - b^3 ?

indigo storm
#

ye

near apex
#

No. Not those.

indigo storm
#

mmm then i really dont know

near apex
#

Oh wait. There is another simpler way.

indigo storm
#

telll

near apex
#

But i dunno if you know that formula.

indigo storm
#

just telll

near apex
#

familiar with this formula?

indigo storm
#

I know

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C+D formule

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RIght?

near apex
#

This one actually.

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You can do directly using this.

indigo storm
#

yeah know those

near apex
#

Great then.

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Do it.

indigo storm
#

ok

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I'll try

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Correct?

near apex
#

Why did you do this?

#

I told you to use this.

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$\cos{(A)} - \cos{(B)} = -2\cdot \sin{\left(\frac{A+B}{2}\right)}\sin{\left(\frac{A-B}{2}\right)}$

ocean sealBOT
#

Enemagneto

indigo storm
#

aaaaaaaaaaaaaaaaah

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u mean I have to take cos 3theta left side

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as minus cos 3A

near apex
#

Yes

indigo storm
#

cos 4A - cos 3A = 0

near apex
#

Yes

indigo storm
#

then formula

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ahh

#

got it

#

thamks

#

this way?

#

well I substituted it

#

maybe it is correct

#

.close

lone heartBOT
#
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ember ridge
#

Hey! What's the logic here?

lone heartBOT
#

@ember ridge Has your question been resolved?

ember ridge
#

<@&286206848099549185>

foggy stirrup
#

notice that in each column a dot is being removed from the shape in the images

ember ridge
#

What about the movement of the pattern in the first column?

#

What differentiates the 2nd and the 5th choice?

lone heartBOT
#

@ember ridge Has your question been resolved?

spiral umbra
#

excuse me

#

I need help with my homework

lone heartBOT
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bleak geyser
#

Send whole question pls

#

!status

lone heartBOT
#
What step are you on?
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2. I have begun but got stuck midway
3. I got an answer but I'm told it's wrong
4. I got an answer and would like my work checked
5. I have a question about someone else's worked solution
6. None of the above
wise jewel
wise jewel
#

like how do yk if it is or not

lone heartBOT
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olive urchin
#

Can someone help me do this integral?

lone heartBOT
olive urchin
#

I think it is multiply by 1 and its probably obvious but I just cant think of what to do

deep hornet
#

Have a look at your integral rules, we have well defined patterns for handling fractions, constant factors and factors with subtractions

lone heartBOT
#

@olive urchin Has your question been resolved?

olive urchin
#

Hmm

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deep robin
#

Is this integral improper?

lone heartBOT
vague coral
#

it is yes

deep robin
#

Bc ln(0) isn't defined right

vague coral
#

it is

deep robin
#

what

vague coral
#

wait ive read your sentence wrong

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ln(0) isnt defined

dim oasis
#

ln(1) is defined, ln(0) is not

deep robin
#

oh ok lol

#

ye thats what i thought

#

Thanks guys 🙂

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autumn crag
#

Another problem i have that i feel i made a mistake somewhere

jagged cobalt
#

are you sure you havent been taught any other methods of differentiation? like the chain rule?

autumn crag
#

It is the very basics i have been taught so far

jagged cobalt
#

i can give you a very quick rundown since it will generally save you a lot of time here

if you have some function like y=sqrt(7-74x)
then you can let u=7-74x
then y=sqrt(u)

from this follows that dy/dx=du/dx * dy/du
which will be dy/dx = -74 * 0.5 *1/sqrt(u)
=-37/(sqrt(7-74x)

autumn crag
#

but my teacher is having a quiz about this tomorrow and isnt allowing me to use different formulas outside of the ones i have been using

jagged cobalt
#

do you have a list of the formulae you can use?

autumn crag
#

yeah in my notes

jagged cobalt
#

may i have a gander

autumn crag
#

imma write them down since i dont have them both in one spot

jagged cobalt
#

damn

jagged cobalt
#

unless this line is just horizontal that cant be right

autumn crag
#

oh yeah cuz you use this equation after

jagged cobalt
#

thats fine and all, im saying youre missing the x in your answer

autumn crag
#

......

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i feel so stupid right now lol

#

thank you

#

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left zealot
#

how do I do this

lone heartBOT
frozen plinth
#

Plug in two x values get 2 y values , draw them and draw a line that goes through them

frozen plinth
#

Pick one x

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Put it in your equation

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And get a y

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And that (x,y) is one point

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Draw it in the coordinate system

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Then do that again for a different x

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Then you have 2 points in your coordinate system, draw a line through them

left zealot
#

I'm not understanding on what ur saying

frozen plinth
#

Well

#

Do you know what it means to plug in a value for x?

lone heartBOT
#

@left zealot Has your question been resolved?

left zealot
#

<@&286206848099549185>

forest cobalt
#

can you create a table of points?

left zealot
forest cobalt
#

So you want to make a graph, right?

left zealot
#

yes

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but how do I start

forest cobalt
#

Okay. You need the points on the graph first

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(x,y)

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x goes left and right, y goes up down

wary stream
#

You were shown this before

left zealot
#

I can't really go down 7

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as there's no space on the graph

forest cobalt
#

there is

wary stream
#

#help-36 message

And no it's not right, because -7/3 can either mean down 7, right 3 or up 7 left 3
This was mentioned too

#

Same logic with -7/5

left zealot
forest cobalt
#

instead of treating it as 7 down and 5 right, you can treat it as 7 up and 5 left

forest cobalt
#

You can, but you said you don't have space, no?

#

So try the other way

wary stream
left zealot
forest cobalt
#

yes exactly

#

now just draw a line between those two points

left zealot
abstract crystal
#

Are you still having concern with the function?

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Yes

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Locate the coordinates by inputting X values and get the Y

left zealot
#

alr ty

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.close

lone heartBOT
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abstract crystal
#

You will have to put the numbers you choose on independent variable(X) and solve it to get dependent variable(Y)

wary stream
#

.reopen

lone heartBOT
#

abstract crystal
#

then find the coordinates from the expression you just got (X,Y)

wary stream
# left zealot so I just have to remember this?

Yes because $-\frac{a}{b} = \frac{-a}{b} = \frac{a}{-b}$ and slope is rise over run so if you did $\frac{-a}{b}$ that means down a units then right b units or if you did $\frac{a}{-b}$ that means up a units then left b units.
$\frac{a}{b} = \frac{-a}{-b}$ so that means if you did $\frac{a}{b}$ that means up a units then right b units and if you did $\frac{-a}{-b}$ that means down a units then left b units

ocean sealBOT
#

dldh06

wary stream
#

.close

lone heartBOT
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languid bolt
#

Okay so,

The general equation of a straight line is y = mx + c
How do I make x = h where h is a real number in that form?

languid bolt
#

like... for example: x = 4

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or you can't?

gray isle
#

you don't

#

that form is only applicable for lines with defined slope

languid bolt
#

ohh okay

#

.close

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earnest current
#

$\lim_{x \to a} c = c$

lone heartBOT
ocean sealBOT
#

texaspb

earnest current
#

hey how do you prove this using the formal definition? feel like this should be a nobrainer but I actually dunno how to write the proof in the most correct way possible

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errant turret
#

Hi I was wondering how I could find the domain of f(x) = 1 + ln(x^2+x-1)

ionic jewel
errant turret
ionic jewel
#

that is not true

ionic jewel
errant turret
#

when i tried to solve whats inside ln(x)

ionic jewel
#

well the trick you need to see is that ln(x) only accepts positive numbers

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so x^2 + x - 1 has to be positive

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and therefore you solve
x^2 + x -1 > 0

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and you get the domain

errant turret
#

i couldn't factor this so I got x(x+1)>1

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x>1 and x>0

ionic jewel
#

That is not a legal math step

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the factoring is right, but whatever you did after is not

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but anyways, have you heard of the quadratic equation?

errant turret
#

yes

ionic jewel
#

well then, you can use that to find the zeroes of the polynomial, then figure out which sections are positive

#

and thats the domain

errant turret
#

thanks, i have figured it out

#

.close

lone heartBOT
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alpine sable
lone heartBOT
alpine sable
#

need help with this, someone help asap

lone heartBOT
#
What step are you on?
1. I don't know where to begin
2. I have begun but got stuck midway
3. I got an answer but I'm told it's wrong
4. I got an answer and would like my work checked
5. I have a question about someone else's worked solution
6. None of the above
alpine sable
#

i need someone to help

#

<@&286206848099549185>

bleak geyser
alpine sable
#

alr

#

@crystal spade

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ok i need help with it all

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cause its confusing

#

can you help me

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im confued

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confused

ocean sealBOT
#

quadrangle

alpine sable
#

0

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to 1.5

#

where

ocean sealBOT
#

quadrangle

alpine sable
#

i got

#

2

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for the second one on the right side

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but idk how to get it for the left side

ocean sealBOT
#

quadrangle

#

quadrangle

alpine sable
#

so now what

#

@crystal spade

#

alg

#

i got all of the side ones btw

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to the right

ocean sealBOT
#

quadrangle

alpine sable
#

i have all of them besides this one now

#

how do i get that one

#

nvm got it

#

600

#

one last thing

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@crystal spade

#

how can i find the domain and range of this

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wait whats the range answer

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cause theres 2 points at the same elevation

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0

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and 4

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im unsure now

#

like

#

x<0?

#

@crystal spade

ocean sealBOT
#

quadrangle

#

quadrangle

alpine sable
#

0≤4?

#

im so confused

#

now

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what would the range be

#

@crystal spade

covert wraith
#

do you still need help ?

lone heartBOT
#

@alpine sable Has your question been resolved?

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alpine sable
#

no

lone heartBOT
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potent oasis
#

Can someone help me and see what I did wrong? We are supposed to use integration by parts but I can’t seem to figure this one out!

sour dove
#

yeah I'd do IPB. You conversion of cos^2(x) = (1 + cos(2x)/2 is correct though. Try setting u = x and dv = (1 + cos(2x)/2 dx and do IBP

potent oasis
#

Ill try that, how do you know which to use as U or as dV

sour dove
#

second sentence 🙂

potent oasis
#

Yes but how do you identify which would be better when you see the problem?

sour dove
#

just as a rule though if you see any power of x most of the time that should be your u

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things like trig functions are cyclic, or e^x is it's own integral, so those are usually great candidates for dV

#

basically your job should be to find the easiest thing as a derivative and more importanly the easiest thing as the integral

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plus, if we did u as a trig fucntion, and x as dV we'd get stuck in a loop as x continued to gain more powers and we'd just to between sin and cos over and over again with derivatives

potent oasis
#

Thats what would happen when i tried it

sour dove
#

yep pretty much

sage hedge
#

.close

sour dove
sage hedge
#

oh sorry

#

I JUST figured they were done cuz its been 12 mins

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and im lost on this calc problem and wanted to use the channel

sour dove
#

nah I don't decide that for them, lol. Often people will go try stuff and come back or take a bathroom break or something

sage hedge
#

oh sorry didt know

sour dove
#

right now it's any of the these

sage hedge
#

I dont see any of them for some reason

sour dove
lone heartBOT
#

@potent oasis Has your question been resolved?

sage hedge
#

ye

potent oasis
#

Ok wait I am still stuck!!! I cant figure out where I messed up

sour dove
#

Here's what I would do to solve this problem.

#

$\int x cos^2(x) dx$. Let $u = x$ and $dv = cos^2(x) = \frac{1}{2}(1 + cos(2x))$. Then $du = 1$ and $v = \frac{1}{2}(x + \frac{1}{2}sin(2x)\$ So then we get $uv - \int v du$, which in turn is this:
$\\ (x)(\frac{1}{2}(x + \frac{1}{2}sin(2x)) - \int \frac{1}{2}(x + \frac{1}{2}sin(2x) dx$. Once again we can integrate to get:
$\int \frac{1}{2}(x + \frac{1}{2}sin(2x) dx = \frac{1}{2}( \frac{1}{2}x^2 - \frac{1}{4}cos(2x)$. All together we get:
$\\ \frac{1}{2}(x)(x + \frac{1}{2}sin(2x) - \frac{1}{2}(\frac{1}{2}x^2 - \frac{1}{4}cos(2x)) + C$

ocean sealBOT
#

MellowDramaLlama

sour dove
potent oasis
#

In the book it says the answer is different

#

It says to Partition the x axis, I am not sure what that means

sour dove
#

here's a breakdown of what they changed

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$sin(2x) = 2sin(x)cos(x)$, so they converted $\\\frac{1}{2}sin(2x) = \frac{1}{2}(2sin(x)cos(x)) = sin(x)cos(x)$. Then we distribute the $\\\frac{1}{2}x$ and we get $\frac{1}{2}xsin(x)cos(x)$

ocean sealBOT
#

MellowDramaLlama

sour dove
#

wait actually I think the book has the last portion wrong

potent oasis
#

really?

#

let me put it into my handy dandy calculator

sour dove
#

so the red line is xcos^2(x). h(x) is the proposed integral from the final answer

#

notice how h'(x), which should be the exact red line, is different?

#

that tells us the answer is incorrect

potent oasis
#

yeah shouldnt it be plus x^2 * 1/4

sour dove
potent oasis
#

yup, im saying in the book shouldnt it be added instead of subtracted?

#

wait im saying thr wrong thing

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im confusing myslef lol

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but shouldnt it be a plus sign in the book instead of a minus sign?

sour dove
#

ah my bad sorry all answers are correct here, they're all just vertically shifted

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let me see if I can explain

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so let's start with the asnwer I got

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graphically we'll start with this

potent oasis
#

how did you get minus 1/4 cos(2x)

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i got plus

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waittttt

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i got it

sour dove
#

ok cool

potent oasis
#

Ok so

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The green is the calculator and the blue is the book

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the black is what I got, which was wrong

potent oasis
ancient saddle
# potent oasis

Hello. I think the only mistake here is the last integral, sin(2x). You forgot the 1/4. Then the rest looks ok, don't forget the parentheses in (2x+sin(2x))

lone heartBOT
#

@potent oasis Has your question been resolved?

potent oasis
ancient saddle
potent oasis
#

Hmm here did I correct it correctly?

ancient saddle
potent oasis
#

Wait

#

Why over 8?

ancient saddle
#

cos(2x)/2 * 1/4 = cos(2x)/8

potent oasis
#

No way

#

You’re right

#

This is aweosme! Thank you so much

#

I have been stumped on this for so long

ancient saddle
#

Ok no problem! It's normal to have some mistakes when doing one or more integrations by parts. Just practice it more, or use the DI method if it suits you (it's just an organized way of doing int by parts)

potent oasis
#

What is the DI method?!

ancient saddle
#

Look it up on youtube 👀 I think mistakes are less probables when you use that 🤔

potent oasis
#

That sounds so cool! I’ll definitely check that out

lone heartBOT
#

@potent oasis Has your question been resolved?

#
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After 15 minutes, feel free to ping <@&286206848099549185>.
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alpine sable
lone heartBOT
alpine sable
#

How would I calculate this?

tardy tapir
#

sub the limit.

#

thats not indeterminate

alpine sable
#

just sub pi into the sin(2x)+1?

tardy tapir
#

yes

alpine sable
#

indeterminate

tardy tapir
#

there are indeterminate forms, in which you cant sub in the limits.

#

like sometimes 0/0

#

its not defined

alpine sable
#

ahhh i see

#

thx

#

so answer is 1

#

sin(360) is 0

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+1

#

is 1

tardy tapir
#

yes, correct!

alpine sable
#

thanks

#

.close

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#
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fallow solar
#

When I look at the irrational numbers in mathematics I think like where tf did these specific numbers come from like pi or e why is pi 3.14.... and not another number

vapid shuttle
fallen verge
#

Just so happened to be that number

vapid shuttle
#

I’d search a video for, why is pi 3.14

#

And similarly for e. Probably those can explain it better than we can

fallow solar
vapid shuttle
#

Are you asking how we calculate pi?

fallow solar
#

Nope

fallen verge
#

Why pi exactly

#

Idk, the universe decided

vale wigeon
#

"why is pi what it is"

vapid shuttle
#

It is that number exactly because that is the relation between the diameter of a circle and it’s circumference exactly

fallen verge
#

Then we get into the discussion of is math invented or discovered

vale wigeon
#

is kind of a philosophical question probably

fallow solar
fallow solar
#

Why did the universe "decide" these specific numbers

vale wigeon
#

there probably is not a "why"

fallen verge
#

It just is

fallow solar
fallen verge
#

Thats like asking why is blue not green?

#

Thats just how it is

zealous lichen
#

well if you are not in Euclidean space pi might be different

#

if you need a reason then pi is 3.14 because we're in Euclidean space

fallow solar
zealous lichen
#

no one assigned them

#

it's a consequence of the axioms of Euclidean space

fallow solar
#

Ok why this specific number

tardy stag
#

shruganime it would have different digits if we were using a different base

#

it's possible to arrive at a formula for π

#

well, an infinite series

#

if you really want to blow your biscuit look at the incomputable numbers

fallow solar
zealous lichen
#

we measure the length of circumference and diameter

#

and their ratio is pi

pale kestrel
#

ask on a philosophy server

fallow solar
zealous lichen
#

?

pale kestrel
#

Let me answer another way

#

The ratio has to be something

#

whether its 1.234567...

#

or 3.141...

#

in any case, youre still going to be asking the same question: why?

fallow solar
pale kestrel
#

So rather than asking your original Q

#

you probably want to figure why ratio of lengths remains the same

#

when scaled

fallow solar
#

Nope

pale kestrel
#

not just a circle

#

The ratio of a square's perimeter to its side length is 4

#

no units also.

#

no matter how big the square is or how its rotated or translated

zealous lichen
tardy stag
#

π is cool and all but what really gets me going is 0.669 or whatever it is

#

the bifurcation constant

fallow solar
zealous lichen
#

so you want to know how to calculate pi

pale kestrel
#

I told you the answer

#

the ratio has to be a constant

zealous lichen
#

bruh

alpine sable
# fallow solar When I look at the irrational numbers in mathematics I think like where tf did t...

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pale kestrel
#

no matter how you scale the shape, this ratio of lengths is a constant

tardy stag
#

it's probably easy enough to show that the ratio must be irrational

pale kestrel
#

Since its a constant, it will be something

#

and no matter what that something is, youll be asking this question, no?

#

pi = 1.234567... why?
pi = 2.3947383746... why?

#

If you want a reason for why its specifically 3.141... though, you should have a look at a geometric proof perhaps

#

approximating pi with polygons, say.

#

That can give you a 'reason', but its up to you whether you want to accept it as intuition

fallow solar
#

You got a point

#

I'm stupid

#

.close

lone heartBOT
#
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hot trail
lone heartBOT
hot trail
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I did term by term...

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it did not cancel out nicely

lone heartBOT
#

@hot trail Has your question been resolved?

hot trail
#

<@&286206848099549185>

undone dune
#

This sum does not converge. It goes to minus infinity.

lone heartBOT
#

@hot trail Has your question been resolved?

lone heartBOT
#
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torn pagoda
lone heartBOT
torn pagoda
#

A bit stuck on assignment b 😅

thorn veldt
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Need help

median oar
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!help

lone heartBOT
#

To ask for mathematics help on this server, please open your own help channel or help thread. See #❓how-to-get-help for instructions.

vale wigeon
#

!noadvert

lone heartBOT
#

Please do not advertise your help channel or thread in other parts of the server. There are many people who need help, and no one person can be prioritized over other people, so please patiently wait. Anyone who chooses to help you is a volunteer who is doing so out of their own kindness.

torn pagoda
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@vale wigeon did my question get overruled? 😅

vale wigeon
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no it didnt we are just redirecting the other person

thorn veldt
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Sorry i dint mean to

torn pagoda
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Thanks for reply! Got confused - No problem @thorn veldt

hard mountain
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Is A supposed to be the bottom or the top of the main pipeline ABCD?

torn pagoda
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Sry, A is the endpoint, in other words the lowest point

hard mountain
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Ok

torn pagoda
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I was trying to make a triangle and find the hypotenuse, But didnt Work out 😅

hard mountain
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Why not calculate from B to E?

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With the same method as you did from A to B

torn pagoda
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I Think that was my first try But somehow i Got wrong result, might try again

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Jesus Christ @hard mountain it did make sense. I just forgot to adjust for not going all the Way from A to D But stopping at B

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Thanks!!

hard mountain
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All good 👍

lone heartBOT
#

@torn pagoda Has your question been resolved?

lone heartBOT
#
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alpine sable
#

hello
Who can explain to me what the backpack problem is?

near apex
#

Ah. That's same as knapsack problem.

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Well, if you need an introduction, it's best if you watch a video or read up on internet.

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If you have doubts about it, then you should delineate those.

lone heartBOT
#

@alpine sable Has your question been resolved?

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limpid abyss
#

I don't get it on how to use L'hopitals rule here/ how to derive this

limpid abyss
subtle birch
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are you supposed to only use L'Hopital?

vale wigeon
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are you required to do this with lhop?

subtle birch
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Because rationalizing the denominator is a better and easier option

limpid abyss
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No, Just trying to practice the l'hopital

alpine sable
#

hello
knapsack problem
who can explain to me?

lone heartBOT
limpid abyss
#

.close

lone heartBOT
#
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Ask your math question in a clear, concise manner.
Show your work, and if possible, explain where you are stuck.
After 15 minutes, feel free to ping <@&286206848099549185>.
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fast nest
#

hi can someone help me

lone heartBOT
fast nest
near apex
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Where exactly are you stuck?

fast nest
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so i’ve done

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hold one

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i have no idea how to do 4-6

near apex
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Okay. So, 4 wants you to write an expression for finding all the ways to go from city 3 to city 2.

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You also can't pass through any city twice.

fast nest
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yes

near apex
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Which means that you can't go through 3 and 2 in between. 3 will just be starting city and 2 will be end.

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Now, how many possibilities do you have for middle stops?

fast nest
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2…?

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wait no

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1..?

near apex
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Which one is it?

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Also tell me what are the choices?

fast nest
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i literally don’t know i’m sorry

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like this assignment has me genuinely so confused and lost

alpine sable
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theres no reason to be sorry

fast nest
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oh ok

near apex
# fast nest i literally don’t know i’m sorry

Try to think at least.
You have to go from city 3 to city 2.
One possibility is that you could just directly go. Right?
Other possibilities are where you choose to take a roundabout i.e. first go to some other city, thence to some other, and so on... finally to city 2. In these cases, you go through multiple in between cities. You don't have many in-between cities to go to, though. Your question has only 4 cities. 2 of which are forbidden so that leaves you with limited options.

fast nest
#

3 to 1 to 4 to 2?

near apex
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Yeah. That's one.

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Any other possibilities?

fast nest
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does it have to go through every city?

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3 to 1 to 2

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3 to 4 to 2

near apex
near apex
fast nest
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thags all of them

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i think at least

near apex
fast nest
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understood

near apex
fast nest
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just 3 to 2?

near apex
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We already saw that. That was the first one i mentioned.

fast nest
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hmm

near apex
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There's one more way where you pass through two cities in between.

fast nest
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idk it’s not coming to me

near apex
fast nest
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4 3 2 1

near apex
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What? No

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You are starting at 3.

fast nest
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oh did you mean

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3 to 4 and so on

near apex
near apex
fast nest
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3 4 2 1

near apex
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No. You have to end up at 2. 😐

fast nest
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ok well you can’t do 3 4 1 2

near apex
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Why not?

fast nest
#

because look at the arrows

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1 can only go to 4

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not the other way around

near apex
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Okay. Good.

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But, you should still count it in your possible paths.

#

Matrix will take care of it automatically.

fast nest
#

oh

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ok

near apex
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When you calculate, that one term will be zero so that whole path would amount to zero.

fast nest
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got it

near apex
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Now, list all the paths together here. Fast.

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So, we get to writing expression.

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We have 5 paths in total.

fast nest
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3 1 4 2

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3 1 2

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3 4 2

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3 2

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3 4 1 2

near apex
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Nice

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Now, for first path - what is the expression ?

fast nest
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would it just be 3 + 1 + 4 + 2?

near apex
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No.

fast nest
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sorry

near apex
#

Look at what it means.

near apex
fast nest
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alright

near apex
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So, First path basically says -
We go from 3 to 1, then from 1 to 4, then 4 to 2.

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How many ways are there of going from 3 to 1 directly?

fast nest
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1

near apex
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Remember, you can answer that from matrix that you made.

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Nice

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Now, you have reached 1. We need to go to 4.

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How many direct ways ?

fast nest
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1

near apex
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Nice

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Now for 4 to 2 ?

fast nest
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1

near apex
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Yes. So overall, we multiply all three.

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1 * 1 * 1

fast nest
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1

near apex
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So, there's only one way.

fast nest
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yes

near apex
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Do you understand why are we multiplying ?

fast nest
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yes

near apex
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Awesome.

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So basically our expression for this just was:
$R_{31} \times R_{14} \times R_{42}$

ocean sealBOT
#

Enemagneto

fast nest
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ohhh

near apex
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For path 3 1 4 2

fast nest
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should i clarify the paths or just simply write the expressions?

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like write the path : expression

near apex
near apex
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Otherwise you can just write expression for all and put a plus sign in between expressions.

fast nest
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yes

near apex
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Nice. Write for other 4 paths. Show me.

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Remember, write in terms of R

fast nest
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alright

near apex
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Don't write actual values.

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You are supposed to write expression.

near apex
fast nest
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yes got it

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r31 * r12

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is that it

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or no

near apex
fast nest
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i should be writing it like this on my paper?

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r34 * r42

near apex
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You can write it there as well but it seems like you are not used to writing in smaller fonts.

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If your teacher will accept it on another paper then you can write there as well.

fast nest
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i can write it smaller

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but that’s how it’s supposed to be written correct

near apex
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Yes. For better understanding, you can write path: Expression thing as well.

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It's just i'm not certain what your teacher wants. Writing "Path : Expression" will sure make it easy for others to understand.

fast nest
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well i could write it above?

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ok i wrote the expression

near apex
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Yeah. That's great.

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Similarly do the rest.

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I believe it's easy peasy at this point.

fast nest
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well could you start me off for 5

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i wanna make sure i have the hang of it

near apex
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Well, try the part a. You will do it.

fast nest
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i use the graph

near apex
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List the possible cases. I'll check.

near apex
# fast nest i use the graph

No. Just list possible paths. See. You have to start at 1 and end at 1.
In between, there can be only one city.

fast nest
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1 2 1

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1 3 1

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1 4 1

near apex
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Yes.

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Now, just use the same formula to calculate.

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This time you need to give values though. Not expression.

fast nest
#

is the first 6

near apex
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Yes

fast nest
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second is 2

near apex
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yes