#help-13

1 messages · Page 426 of 1

slender holly
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then move it untill x is -3*

pastel vault
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the graph starts from x = -8
okay, so y = (x + 4)^2 and y = (-8 + 4)^2 = 16, so that's out of the graph

draw the curve, but then you stop your pen when x = -3

slender holly
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curve doesn’t have to be perfect ?

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why does it look like this

pastel vault
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so here's a task for you: write down a table on a blank sheet paper

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you have x = -6, 5, -4, -3, -2

slender holly
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i gotta graph too

pastel vault
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and you want to sub in these values of x into y = (x + 4)^2

pastel vault
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find all the values of y

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then plot them on the graph

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make a curve that passes through all the points you plotted

slender holly
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the x values matter or no

pastel vault
slender holly
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ya but if i wanna do a different equation what x values do i use

pastel vault
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but you can use any x values

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they just have to be close enough, like say 1 apart

slender holly
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oh ok so for -6

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it would be

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4

pastel vault
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yep, (-6 + 4)^2 =4

slender holly
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did u forget the negative on 5

pastel vault
slender holly
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is it like tha

pastel vault
#

yep! that's correct

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that was fast

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okay so now you need to plot those points

well, y = 9 is outside the graph so you don't need x = -1

slender holly
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but i thought x can’t go past -3

pastel vault
slender holly
#

ok

pastel vault
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if you draw the curve, you can just erase the part to the right of x = -3

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that's why you really shouldn't draw graphs in pen btw

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pencil is the best

slender holly
#

so like ts

pastel vault
#

minor correction, x = -7 already gives y = 9

slender holly
#

wait huh

pastel vault
#

should be like this

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the graph gets very steep there

slender holly
#

oh okay so is that the answer

pastel vault
#

indeed

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you remembered the white circle thing, cause x < -1 means that x = -1 is not included

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so that's now correct!

slender holly
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so that’s both ?

pastel vault
pastel vault
slender holly
#

uh liek this

pastel vault
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maybe just draw a line at this point between x = -7 and x = -6

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the line does not intersect x = -7 at all, cause it goes out of the graph

slender holly
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oh

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do say anything yet

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imma do the first part and tell me if it’s wrong

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1 sec

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ignore the curve

pastel vault
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omg, it's x less or equal to -3, so you were close

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a tip is that the functions are usually in order from left to right

slender holly
#

oh i

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i read it wrong

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is it just the other way then

pastel vault
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and you still need that black dot at x = -3

slender holly
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can u help with the second part i haven’t seen that before

pastel vault
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draw y = 3, but you start at x = -3 and you finish at x = 4

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and you need white dots for both endpoints, cause you have < and <

slender holly
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oh that’s easy

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lemme try the last part with what i told me

pastel vault
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yes that quadratic is very similar to the one you did in q1

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it has that zero at x = 5 though and you start at x = 4

slender holly
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nevermind i forgot

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can u remind me

pastel vault
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it's vertically symmetrical

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so that means here, x = 4 and x = 6 have the same y-value (1)

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if you make a table of values for x = 4, 5, 6, 7

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y = .........

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plot the points and join the curve as before

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you'll see what I mean

slender holly
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correct

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?

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so i should make a table before i graph

pastel vault
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now with your table, plot the points and join them using a curve

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and then you also have the 'really steep' thing where your graph escapes upwards

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so it never hits x = 8 (cause y = 9)

slender holly
pastel vault
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I know it's hard to draw

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just want to make sure you know what's actually happening with the graph

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oh right, your circle at x = 4 should be filled in

slender holly
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are u sure because there is no underline

pastel vault
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oh nvm

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I thought I saw one

slender holly
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ok this one really confused me me

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because it’s doing extra stuff with the first part instead of just a number

pastel vault
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ah, those are just lines like in q2

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lines are easy, you just pick two points

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say for x + 2, when x = -8, y = -6

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and x = -4 gives y = -2

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join the two points, think about whether the circle should be white or black, and that's it

slender holly
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oh okay point doesn’t matter ?

pastel vault
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yes, which x-values you do isn't too important

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you can just use x = -4 and x = 3 for the next one also

slender holly
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did i completely mess it up

pastel vault
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if you plot (-4, -2)

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keep (-8, -6) the same except there's no white circle there

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then draw a straight line as best as you can

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you should get it

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okay I have to go though

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no worries, you can just close this one and make a new channel so that it goes to the top

slender holly
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aw ok

cedar kilnBOT
#

@slender holly Has your question been resolved?

cedar kilnBOT
#
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gray stirrup
#

how does this work?

cedar kilnBOT
worldly chasm
#

@gray stirrup which part?

gray stirrup
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how the r is negative

worldly chasm
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I'm assuming this is a solution

gray stirrup
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when x = -r/ sqrt 10

worldly chasm
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I'm assuming that it's using the fact that cosine is negative in the 2nd quadrant

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the cosine corresponds to the x-coordinate of a point on the unit circle with an angle theta from the positive x-axis

gray stirrup
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when its sin theta r is also negative tho

worldly chasm
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and so when the angle is in (90, 270) degrees the x coordinate is negative.

worldly chasm
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just we eventually get a positive answer, because a negative times a negative is positive.

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(-3 and -r/sqrt(10))

gray stirrup
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if the line was in the 3rd quadrant whould r be postive since neg times neg is pos?

worldly chasm
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if the line was in the 3rd quadrant then the slope would be positive

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so the y coordinate would be negative (because neg times pos is neg)

gray stirrup
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sorry but i still dont get it

worldly chasm
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no worries.

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talk me through what you do understand.

gray stirrup
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since the slope is negative r is negative?

worldly chasm
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no

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x is negative, r is not negative

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and x is negative because we're in quadrant 2.

gray stirrup
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if we were in qudrant 4 and x is postive while y is negatvie how woudl that affect it?

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.close

cedar kilnBOT
#
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gray stirrup
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thnak you for your help @worldly chasm

worldly chasm
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sorry

gray stirrup
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its good

worldly chasm
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If we were in quad 4, then x is positive and y is negative

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a line here would have a negative slope

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so you would have x be positive, and y be formed from (pos x value time neg slope = neg)

gray stirrup
#

ty

cedar kilnBOT
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tidal turret
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Hello, I need help figuring out whats the next step after trying to solve this inequality

chrome elk
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Somehow in solving this you have got rid of the inequality

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Bring it back and that should help

tidal turret
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So by going back to the 2nd step before I did the factoring thingy?

fair peak
#

Is answer x belongs to (-5, -3) U (-1 , infinity)

chrome elk
cedar kilnBOT
chrome elk
dry stump
chrome elk
#

You are both ignoring the glaring issue here

tidal turret
chrome elk
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Sure but what happened to the >

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You moved the fraction from the RHS to the LHS

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So what's left on the RHS

tidal turret
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In that part, i was following along with a classmate's notes and I kinda assumed the > part was not neccessary anymore for the equation...

dry stump
#

He subtracted the right fraction to itself and combined it with the other on the left, so the right is 0

cedar kilnBOT
#

@tidal turret Has your question been resolved?

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balmy prawn
#

is sin more appropiate or cos

cedar kilnBOT
buoyant latch
#

They both can work

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But what does the mnemonic say?

balmy prawn
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how do u determine if u should us sin cos or tan

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btw whats mnemonic?

neon void
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draw the triangle on a circle

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with the angle corner at the center

balmy prawn
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done

neon void
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ok great can i see it

buoyant latch
balmy prawn
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the quality of my laptop is horror but i did it on my paper

neon void
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ion really like mnemonics they dont realy teach you anything

balmy prawn
buoyant latch
#

That’s a mnemonic

balmy prawn
#

ohh

buoyant latch
#

It’s just some letters or phrase that helps you remember something

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In this example it should help you remember which one to use

balmy prawn
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so all sin cos tan do is show the ratio

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of two line

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right

buoyant latch
#

Yeah

balmy prawn
#

ohh so it doesnt really show u the length of one line

buoyant latch
#

They do do a bit more than that but you don’t have to worry at the moment

buoyant latch
neon void
#

have you gone through the unit circle and all that yet

balmy prawn
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i just started

neon void
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💀 can ppl teach trig right for once

buoyant latch
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What does the mnemonic mean?

balmy prawn
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sooo sin cos tan ONLY shows the ratio between the line and the hypotenuse

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not the opposite to the adjacent or smth

neon void
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that's tangent

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sin cos is ratio of a leg of the triangle to the hypotenuse

balmy prawn
#

waitt so can u summerise it

neon void
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no

balmy prawn
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so i can turn this to notes

buoyant latch
#

Suppose I have a right angles triangle

neon void
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thats why im asking you to draw circles

buoyant latch
#

Could you tell me what the letters in sohcahtoa stand for

neon void
#

dang why cant i remix on mobile

balmy prawn
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s= opposite over hypotenuse

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c= adjacent over hypotenuse

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t=opposite over adjacent

buoyant latch
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sin(θ) = …

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Yeah

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Okay so which is opposite which is adjacent which is hypotenuse in the picture

balmy prawn
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the line on the left vertical side is opposite, the line on the up side is hypotenuse, the last one is adjacent

buoyant latch
#

Good

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So sine says sin(θ) = vertical line / hypotenuse

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If I know what the vertical line is, say 3, and the angle θ is given, could you tell me what the hypotenuse is?

balmy prawn
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uhm

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so its 3 over hypotenuse

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or smth

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its ok gng

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imma go eat dinner and come back later

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.close

cedar kilnBOT
#
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limber bone
#

ello @here, could some1 help me w this, idk how to solve for z

slender ginkgo
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try

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simplifying

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${\frac{z+4}{z+4i}}$ and ${z = x + iy}$

wraith daggerBOT
slender ginkgo
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then compare the im and re parts

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@limber bone

limber bone
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there'd be z^2?

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@slender ginkgo then what to do from here?

slender ginkgo
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can u show what u get

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[ \frac{(x+4) + iy}{x + (y+4)i}]

wraith daggerBOT
limber bone
slender ginkgo
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cool

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${z^2 = x^2 + 2xyi - y^2}$

wraith daggerBOT
limber bone
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@slender ginkgo

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@here, help ;>

slender ginkgo
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u kinda need to summarize more

slender ginkgo
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[ \frac{(x+4 + iy)(x - i - 4y)}{x^2 + (y+4)^2}]

wraith daggerBOT
slender ginkgo
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,w expand (x+4 + iy)(x - 4i - yi)

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[ = \frac{(x^2 + 4x + y^2 + 4y) + (-4x -4y - 16)i}{x^2 + (y+4)^2}]

wraith daggerBOT
slender ginkgo
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now notice

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${\frac{z+4}{z+4i}}$ is real

wraith daggerBOT
slender ginkgo
#

@limber bone

fair peak
cedar kilnBOT
#

@limber bone Has your question been resolved?

cedar kilnBOT
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upper ruin
cedar kilnBOT
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wraith daggerBOT
#

Alberto Z.

cedar kilnBOT
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languid crystal
#

anyonne know how to do 7c

cedar kilnBOT
urban coral
#

you're probably supposed to find the height of the pole using the angle of elevation of V from A, then use that in a trigonometric function to find the angle stated in c.

languid crystal
#

i got that part i js have no idea how to find the height of the pole

urban coral
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consider drawing the triangle formed by C, V and A

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after filling in the given information, you should be able to see which function you'll need for the job

languid crystal
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for the triangle i only have one angle and one side tho

urban coral
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that's good enough

languid crystal
#

i dont think ive learnt any formulas with only those variables

urban coral
#

have you learnt about inverse trigonometric functions?

languid crystal
#

like cosec, cot, and sec

urban coral
#

not those

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as in arcsin, arccos, arctan (or sin^-1, cos^-1, tan^-1)

languid crystal
#

yes

urban coral
#

you'll have to use one of those

languid crystal
#

but the triangle isnt right angled

urban coral
#

actually no come to think of it, you don't need to use one of those

urban coral
#

the pole is vertical

languid crystal
#

yes but isnt v o nan elevation from a of 30 degrees

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so one of the angles is 30 degrees

urban coral
#

does that forbid CVA from being a right triangle?

languid crystal
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it doesnt look like a right angle

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are we assuming its just a right angle

urban coral
#

we don't need to assume

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the plane containing A, B, and C is horizontal

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and the pole is vertical

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assuming no funny shenanigans (which I doubt there is), you have a clear right angle between the pole and the plane

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imagine looking at CVA from the side

languid crystal
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ah ok i do not understand the meaning of vertical and horizontal plane

urban coral
#

do you understand the concept of vertical and horizontal then?

languid crystal
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yeah i do now

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i thought it meant like a vertical down from c

urban coral
#

so now can you draw the triangle CVA?

languid crystal
#

yes let me see

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33.42 degrees?

urban coral
#

what?

languid crystal
#

for the elevation of V from P

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the answer

urban coral
#

well I haven't calculated it myself, but if you want to show your working leading up to it, I can check that for you

languid crystal
#

$30\cdot tan(30)=\sqrt{3}a$

wraith daggerBOT
languid crystal
#

$tan^-1(\frac{\sqrt{3}a}{\frac{21a}{8}})=33.42 degrees$

wraith daggerBOT
urban coral
languid crystal
#

oh i mean 3a times by tan

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PC is from part b

urban coral
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and sqrt(3)a came from...?

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oh you didn't use a variable for the height of the pole, I see

languid crystal
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tan(30) is sqrt3/3

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yh i js solved it

urban coral
#

hm, usually recommended to state what you're solving for

languid crystal
#

yeah probably a good idea

urban coral
#

,w arctan(8sqrt(3) / 21) in degrees

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eh why am I doing an arctan

languid crystal
#

isnt arctan right

urban coral
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hold up I'm confusing myself

languid crystal
#

isnt it in degrees

urban coral
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ah ok

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earlier it was in radians

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then yeah, works

languid crystal
#

hooray it is right

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wait can u help me with one more question

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its js clarifying somethig

urban coral
#

do send it

languid crystal
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ok its js the part b of that question

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to prove PC = that do you use the bisector method thing

urban coral
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I'm not too sure about this particular one, sorry

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but I suppose I can check any working for you to see if it's logical

languid crystal
#

ok so bisector theorem states that uh

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$\frac{AB}{AC}=\frac{PB}{CP}$

wraith daggerBOT
languid crystal
#

$\frac{5a}{3a}=\frac{5}{3}=\frac{AB}{AC}$

wraith daggerBOT
languid crystal
#

then $\frac{PC}{PB}=\frac{AC}{AB}=\frac{3}{5}$

wraith daggerBOT
urban coral
#

looks right then

languid crystal
#

yeah uhhh

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$PC=\frac{3}{3+5}BC=\frac{3}{8}(7a)=\frac{21a}{8}$

wraith daggerBOT
languid crystal
#

problem is i have no idea how does that 3/(3+5) show up

urban coral
#

well, you split BC into BP and PC in the ratio 5 : 3

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so there are a total of 8 parts

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3 of which belongs to PC

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that's how you get it

languid crystal
#

oh 😭

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fair enough

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thanks for ur help

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ppreciat eit

urban coral
#

nps. anything else?

languid crystal
#

nah thats all

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how do i close the thing

urban coral
#

type .close

languid crystal
#

.close

cedar kilnBOT
#
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cedar kilnBOT
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silent stratus
#

Pls help me memorize the table of 14 I am in 9th class tho 🥲🥲

tropic oxide
#

"table of 14"?

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what does that mean?

silent stratus
tropic oxide
#

i would imagine in the same way as you learned the rest of your times tables

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but also tbh i don't see the point

silent stratus
#

We should know tables from 1 to 20 for fast calculation but ik till 13 only 😭

tropic oxide
#

if you need to multiply something by 14 in your head, why not do it as ×7×2

tropic oxide
#

that's a lot.

silent stratus
tropic oxide
#

but even then, i don't think 14 is magical. you learn it the same way as any others.

silent stratus
#

Is there any trick?

tropic oxide
#

no

silent stratus
#

How many do you know?

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How you learnt them?

tropic oxide
#

i don't remember a lot about how i learned the times tables cause it was really long ago

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but one thing that i think helped me was skip-counting

silent stratus
last apex
#

Learning to do long multiplication fast will be more beneficial

silent stratus
#

How can I do fast

last apex
#

Practice

silent stratus
silent stratus
tropic oxide
#

reciting one row of the table in order

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such as: 7, 14, 21, 28, 35, 42, 49, 56, 63, 70

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or:
13, 26, 39, 52, 65, 78, 91, 104, 117, 130

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and then just do that a whole bunch of times until it sticks in memory

last apex
#

Just add 13/7 over and over

tropic oxide
#

13 or 7 or whatever other number you're learning the row for

silent stratus
urban coral
#

what kind of pace are you expected to keep up with in exams that you can't afford to take 30 seconds off to do some 2-digit by 2-digit multiplication though

silent stratus
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This time would be utilised for checking

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40min are alot

urban coral
#

I never said 30 seconds is nothing.
I'm asking what kind of pace are you expected to keep up with that a 30-second calculation (frankly speaking, 30 seconds is overestimating and kind of a worse case scenario anyway) is too much.

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but if that's the case, I suppose other than raw memorizing the multiplication tables, you could use some tricks like x5, x9, x11, etc.

urban coral
#

x5 = x10 / 2
x9 = x10 - original
x11 = x10 + original

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amongst some others

silent stratus
#

Not other

urban coral
#

I mean, x15 = x10 + x5

silent stratus
#

I searched a lot on yt

silent stratus
urban coral
#

then gotta practice, I suppose?

silent stratus
#

By the way yk , any trick to memorize squares from 21 to 30

silent stratus
urban coral
#

...is there another method though? even if you find another method, you still have to practice with it to make use of it efficiently and correctly

silent stratus
deep token
# silent stratus That's what everybody says

Well yeah because it's true. There isn't exactly a shortcut to remembering/learning itself; but I do suggest that on the weekends, maybe try to do some exercises for you to decrease the general time you take in solving.

urban coral
#

maybe get someone to toss you question after question

urban coral
#

but there is no shortcut to success unfortunately, not even for that new question you asked

#

well, 30^2 is kinda shortcut-friendly

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since it's just 3^2 with two zeroes after it

silent stratus
#

I tried making any funny mnemonic but not able to

deep token
#

And even if you memorize the product down to the T it'd do nothing against needing full solution for the computation

urban coral
#

but other than that, either you'll have to memorize or calculate, or if you're a madlad, remember that consecutive squares differ by consecutive odd numbers

#

still, you'd need to do some calculation.

urban coral
#

ignore that word if you don't know what it means

#

not important for the context

deep token
#

Also a trick my classmates use is writing something over and over again until they manage to get it; again, time consuming, because everything takes time whether you like it or not.

urban coral
#

wait wait wait. are you thinking you can get good without effort?

silent stratus
deep token
urban coral
#

unless you're some mental math god that sees answers as quickly as they come, you're gonna have to put some effort into making it work for you first, then you can focus on going faster

silent stratus
#

Fast as calculators

deep token
urban coral
#

well for that

#

either you are super talented (I know of one of my teachers who can), or super hardworking

silent stratus
urban coral
#

maybe every weekend, take half an hour to an hour out and do arithmetic questions

#

focus on accuracy first, then build speed without sacrificing accuracy

deep token
silent stratus
#

But am normal

deep token
#

So, having said that, just like Mikya (and I from a few minutes ago?) said, you're gonna have to sacrifice some of your time for building your skills in mathematics. Start simple, and build onto the difficulty.

urban coral
#

either you are super talented (I know of one of my teachers who can), or super hardworking

deep token
silent stratus
silent stratus
urban coral
deep token
urban coral
#

besides, I said, half an hour to an hour per weekend

#

surely you can dedicate just that much time...?

silent stratus
#

Hm

urban coral
#

I'm not asking you to sell your soul by doing 10 hours of practice every day

silent stratus
#

Thanks for guidance everyone

urban coral
#

!done, if nothing else

cedar kilnBOT
#

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limber bone
#

hi @here, could some1 tell me where have i made a mistake, i checked markscheme and c should have been (11/18) instead of (11/6)

vestal bluff
#

its the same thing

#

you moved the 3 to the sin2y

#

so your c is 3 times more

limber bone
#

lol, 3c = (11/6) ig

#

thzz,

#

.solved

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topaz hinge
#

Given triangle SAE. Let D be the midpoint of AE, I be the midpoint of SD, and K be the intersection point of AI and SE. Find the ratio IK/AI.

I've tried calculated SK/KE = 1/2 but stucking there. How can I calculate the ratio?

cedar kilnBOT
#

@topaz hinge Has your question been resolved?

topaz hinge
#

<@&286206848099549185>

honest field
#

hmm how did you calculate SK/KE = 1/2

topaz hinge
#

using the manelaus theorem $\frac{SK}{KE}\times\frac{EA}{DA}\times\frac{DI}{IS}=1$

wraith daggerBOT
honest field
#

alright nice

#

now apply the Melenaus theorem to ∆AEK with line SID intersecting it

topaz hinge
#

woah, let me try it

honest field
#

Alternatively you can apply Melenaus theorem to ∆AID and line SKE right from the start

topaz hinge
#

omg thank you so much!!! I didn't see these at the first place

#

it's kinda hard to see

#

.close

cedar kilnBOT
#
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honest field
#

me nhật 💀

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grave sentinel
# cedar kiln

My question is what are some good resources to study for AMC10 and AIME?

grave sentinel
#

Can someone please help

#

idk

#

ig no one

#

.close

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grave sentinel
#

.reopen

cedar kilnBOT
grave sentinel
#

Guys please help

#

Like I am using these boooks

#

and AoPS Math JAMS, AoPS Math Wikis, AoPS Math Classes...

#

.close

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#
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grave sentinel
#

.reopen

cedar kilnBOT
grave sentinel
#

Gng pls help

cedar kilnBOT
#

Please don't repeatedly close and claim a new channel with the exact same question. This erases all previous progress made towards your problem and is confusing for helpers, making it more difficult to help you. Please be patient, even if your channel has not received much attention.

#

@grave sentinel Has your question been resolved?

hexed parrot
#

what do u need help with broo

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obtuse coral
#

This is the graph of the first derivative. Knowing that, where is the original function concave up/down?

severe cipher
#

can y'all help me with something

worldly chasm
cedar kilnBOT
worldly chasm
obtuse coral
#

.close

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#
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obtuse coral
#

Thank you, tho

#

.close

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inner sandal
#

guys can someone help me with this it’s actually pissing me off I been at it for like 3 hours

neon void
#

well you should break it up into two inequalities first because of the absolute value

inner sandal
#

yes I get that I make it once with > and once with <

#

but after I solve it my answer is different than the model answer

#

like they want me to do all of this and it’s so confusing

dreamy void
#

you also have to keep in mind that multiplying by x+2 might change signs

inner sandal
#

like how did we find out -2 is part of the X value just because it’s in the denominator while in the second inequality the X value is root 13 but in the first inequality when we solved it we got 1 excluded from the set

inner sandal
#

someone helpppp

#

pls

#

I been at this for 3 hours lowkey

dreamy void
#

Can you rephrase your question a bit more clearly?

inner sandal
# dreamy void Can you rephrase your question a bit more clearly?

ok so in the first step of solving the denominator can’t be 0 so x≠2 but then at the end of the first part of solving the domain is -2 but then for the second inequality we also establish that x≠2 but when we get the domain it’s -infinity and -root13

dreamy void
#

So your question is, how we get ]-oo, -sqrt(13)[ in the last part?

#

It helps to draw this on a number line

#

,calc sqrt(13)

wraith daggerBOT
#

Result:

3.605551275464
dreamy void
#

So you would notice that -sqrt(13) which is -3.605.. is smaller than -2, so their intersection would result to starting at -sqrt(13), not -2. For example, say we had x=-3 which satisfies x<-2 but you'd get a wrong answer for x<-sqrt(13) since -3 is greater than -sqrt(13).

inner sandal
#

OHHH

#

SO BECAUSE root 13 is less than -2 so we used root 13 for the domain

#

but 1 is bigger than -2 so when we got it we excluded it from the set in the final answer

dreamy void
#

in other words the strict inequality makes us exclude x=1

inner sandal
dreamy void
#

questions like that are hard to answer, you have to think logically

#

like

#

If you drew y=(x-1)^2

#

and you wanted to see when it's positive you would realize it's if x is not 1, because at 1 it has a root

#

all you gotta do is think about your simplified result in the end, and what it means

inner sandal
#

okay I kind of get you

dreamy void
#

sometimes it helps to draw a picture instead of doing everything algebraically

inner sandal
#

could you explain this part too

#

I’m a bit confused why we need to reverse the inequality symbol and do it twice

#

for each inequality so four times total

dreamy void
#

After resolving the abs value you have two inequalites

#

If you consider one of them, you get again two cases

#

because when you multiply by x+2 both sides, the < sign might flip, depending whether x+2 was positive/negative

inner sandal
#

ohh

#

OHH ALRIGHT

#

I got itt

dreamy void
#

you are basically slicing a big hard problem into 4 smaller ones

dreamy void
#

because they are easier to work with

inner sandal
dreamy void
#

and in the end you combine the solutions

inner sandal
#

like why we’re even doing all that

inner sandal
#

okay thanks a lot

#

how do I end the

#

help

dreamy void
#

type .close

inner sandal
#

okay thanks

#

.close

cedar kilnBOT
#
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modest sky
cedar kilnBOT
modest sky
#

how do i answer number 27 ?

neat dune
#

What have you tried?

modest sky
#

so like ik the formula is area for sector
theta / 360 x pi x r^2

#

but how do i like get the value of theta

neat dune
#

Well, you don't need theta here. It tells you it's divided into 20 congruent sectors. So each sector is 1/20th the total area.

modest sky
#

ohh

neat dune
#

yup 😄

modest sky
#

OK THANKYOU

#

.close

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#
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slender prism
#

How do I divide polynomials using synthetic division and two known factors
I don’t know if this is against server rules or anything it’s not a test but it’s my homework and I wasn’t here for it

I looked everywhere online to try and find how to answer this question and I think I know how to use synthetic division now but I’m not really sure what to do

The actual problem is this: The polynomial function
f(X)=2x^4 - 7x^3 - 2x^2+13x+6 has
known factors (x + 1) and (x - 2). Using synthetic division or diagrams, write the polynomial function as a product of linear functions. Show ALL your work and upload the paper.

I also don’t know what “write the polynomial function as a product of linear functions” means either

I also just joined this server so if im not following a rule or something sorry

carmine bronze
#

Linear functions likely means linear factors as in (x - a).

cedar kilnBOT
#

@slender prism Has your question been resolved?

slender prism
#

Oh ok

#

.close

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obtuse coral
#

Not sure whether my q was answered in a different channel

#

I lost it

obtuse coral
#

Anyway, I need help graphing this out

#

My teacher drew smth like this, but I’m not sure how it’s right

cedar kilnBOT
#

@obtuse coral Has your question been resolved?

cedar kilnBOT
#

@obtuse coral Has your question been resolved?

cedar kilnBOT
#

@obtuse coral Has your question been resolved?

compact jay
#

second derivative is showing concavity

obtuse coral
compact jay
#

the thing u attached looks correct

obtuse coral
#

That looks like concave down to me

compact jay
#

it’s concave up just the other half isn’t in the graph

#

for reference

#

that’s how I understand it

obtuse coral
#

I don’t really understand this part of what you drew

#

@compact jay

#

That part’s drawn as concave down when in reality it should be concave up

#

Right?

#

Nvm

#

.close

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#
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lost aurora
#

A geometry student wants to draw a rectangle inscribed in a semicircle of radius 8. If one side
must be on the semicircle's diameter, what is the area of the largest rectangle that the student
can draw?

lost aurora
#

u have to use optimization

hallow pelican
#

so like, calculus

lost aurora
#

yeah basically

hallow pelican
#

dumb question. tell the teacher that solution methods dont matter

lost aurora
#

its an optimizaiton unit, so u kinda have to use that

#

i got a horrible teacher

#

but yk how to do it?

hallow pelican
#

mhm

lost aurora
#

can u teach me

hallow pelican
#

is this you?

#

so, what relation does x and y have?

lost aurora
#

but it says one side must be the semicircles full diameter

#

so doesnt it have to cover the whole semi circle's diameter

hallow pelican
#

that doesnt make sense at all

upper ruin
#

Read more carefully

hallow pelican
#

it says "on"

lost aurora
#

okay i see

#

so then how do i approach it from there

hallow pelican
lost aurora
#

oh

#

mb

#

x is the radius?

#

i mean xy=A

hallow pelican
#

x is a side length...

lost aurora
#

yeah

hallow pelican
#

think about x and y for a moment

lost aurora
#

they both are side lengths of the rectangle

#

?

hallow pelican
#

exactly

#

so

lost aurora
#

if u multiply them u get the area

#

?

hallow pelican
#

am i going to drop a huge tip? tick for yeah cross for no

#

they are related by the pythagorean theorem

lost aurora
#

ohhh

upper ruin
#

Hint: draw a suitable radius

lost aurora
#

wait give me a second to try it now

upper ruin
#

And you'll see why/how

lost aurora
#

is it x=4 and y= root 48

upper ruin
wraith daggerBOT
upper ruin
#

Awful mistake!

hallow pelican
#

why did you simplfy the square root like that😭

lost aurora
#

oh shit can I not

upper ruin
#

Of course not!!

#

$$\sqrt{A + B} \neq \sqrt{A} + \sqrt{B}$$

wraith daggerBOT
#

Alberto Z.

lost aurora
#

Sorry give me a sec I’m solving it

upper ruin
wraith daggerBOT
#

Alberto Z.

upper ruin
lost aurora
#

ohhh yeah ur right

#

but do I use product rule

#

for some reason I feel like I made it so complicated

upper ruin
upper ruin
lost aurora
#

Wait nvm

#

Sorry I’m stupidly

upper ruin
wraith daggerBOT
lost aurora
#

I brought it to the other side

upper ruin
#

Wait, is x half or the whole side length?

lost aurora
#

Half

upper ruin
#

Alright, then the area is 2x•y

lost aurora
#

oh shoot okay

#

Why is thst tho?

#

Is it not x/2 * y

#

Bc half the side length

upper ruin
lost aurora
#

Oh wait ur right oops

upper ruin
#

You could do it the other way round (hence x being the whole base), but then inside the root you'd have an x²/4 which is unpleasant for the calculations

lost aurora
#

I’m stuck

upper ruin
wraith daggerBOT
upper ruin
#

You forgot the chain rule 😬

lost aurora
#

oh shoot UR ROGHT

cedar kilnBOT
#

@lost aurora Has your question been resolved?

cedar kilnBOT
#
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torn marsh
#

for the phase shift, can we have h units shifted to the left?

torn marsh
#

as well

#

and how would it be written

dusk goblet
long swan
#

f(x+h)

#

Haha

torn marsh
#

ohh ok thanks

#

.close

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#
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vernal kite
#

how do i do this

cedar kilnBOT
vernal kite
#

i expanded the thing inside the bracket

#

then x = 0 so i got (iy - 6) / iy

#

now idk what to do

sonic thicket
#

Why x = 0 ?

vernal kite
#

bc the real part of that = 0

hollow trail
#

the real part of (z - 6)/z is 0, not the real part of z

sonic thicket
vernal kite
#

and then expand

sonic thicket
#

What did you get after expanding? Without setting x = 0

vernal kite
hollow trail
#

so take the real part of the entire expression (z - 6)/z

vernal kite
sonic thicket
#

Remove the complex number from the denominator

vernal kite
#

so (x - 6)/(x) = 0

#

therefore x = 6

#

?

tacit girder
#

Yes x=6

#

Because denominator can not be x=0

vernal kite
#

yea

#

but then how do i find y

tacit girder
#

Clearly y=0

vernal kite
#

so x = 6

tacit girder
#

x(x-6)+y^2/(x^2-y^2)=0

vernal kite
#

it’s a vertical line?

#

oh

#

real-ise the denominator?

tacit girder
#

You don't need to find the values

#

Just look at the numberator

#

x^2+y^2-6x=0

vernal kite
#

so if x = 6, y = 0

vernal kite
tacit girder
#

as I said by simplifying the given equation

#

z=x+iy

vernal kite
#

.close

cedar kilnBOT
#
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magic solar
#

Could anyone help with proving Wilson’s theorem and converse

magic solar
#

If (p-1)!+1 is divisible by p, p is prime & the converse too pls

hot cipher
#

Theres such a neat way of proving this one

#

Wilsons at least

#

Well, I hope you know what a Field is, and that you can agree with me that Z/pZ is a field.

magic solar
#

Idk what that is

#

Is there any algebraic way

hot cipher
#

Do you know about mod n?

magic solar
#

Idk about modular arithemetic either

hot cipher
#

🥀

magic solar
#

But like I get what it is

#

Sorta

#

Just don’t know notation

hot cipher
#

If you dont really know what it is, then it will just be a big "believe me" tbh

#

i think it can be done with residue anyways

magic solar
#

Surely there is an algebraic method

last apex
hot cipher
last apex
#

But ikwym

hot cipher
#

Z/pZ is a field way of proving it is so clean tbh

magic solar
#

I’m guessing z/pz is some integer prime field or some shit

#

Idk allat though

hot cipher
#

I can give you the basic rundown of it

magic solar
#

Umm sure

hot cipher
#

Basics of modular arithmetic:
Z is the set of integers
nZ is the set of all the integers multiples of n.
Z/nZ is what we call a partition / quotient modulo n

I think you know what a remainder is

Well, it divides integers based on remainder when dividing by n

#

for example:
any number divided by 2, can only have either remainder 0 or 1 (aka its even or odd)

#

therefore, Z/2Z only has two elements
${[0]_2,[1]_2}$

wraith daggerBOT
#

∫ᴄ 𝐅·𝑑𝑟 = ∬ʀ ∇⨯𝐅 𝑑𝐴

magic solar
#

Sure

hot cipher
#

Where [0] and [1] are sets themselves, and we call them modulo classes. For the general idea, just know that classes share a lot of properties within themselves

#

Well, any Z/pZ is what we call a field

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Which, apart from a few basic properties of arithmetic, have the added benefit that all elements have an inverse under multiplication

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Z/pZ has p elements, ${[0]_p,[1]_p...[p-1]_p}$

wraith daggerBOT
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∫ᴄ 𝐅·𝑑𝑟 = ∬ʀ ∇⨯𝐅 𝑑𝐴

hot cipher
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Since we know its a field, all elements (except 0) have an inverse.
sooo, if we do

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$[1]_p\cdot [2]_p...\cdot [p-1]_p$

wraith daggerBOT
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∫ᴄ 𝐅·𝑑𝑟 = ∬ʀ ∇⨯𝐅 𝑑𝐴

hot cipher
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Then there must be a way to arrange all elements (except 1 and p-1) such that its paired to its inverse.

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mb, missed the actual -1, the idea is the same, just that you pair all elements minus the first and last (1 and p-1)

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The others become 1, so you are left with p-1

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which has remainder congruent* to -1
had a brainfart for a sec

magic solar
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Tbh this is a bit much

hot cipher
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the closest youll get to "algebraic" is using division with remainder

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But tbh, its arguably messier than this

cedar kilnBOT
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@magic solar Has your question been resolved?

cedar kilnBOT
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cedar kilnBOT
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split cave
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hi is this an example of if A then B? x<5 -> x< or equal to 5

split cave
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if A is true and B is false then its false

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but how do I know which one is A or B?

maiden dune
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I mean if A is True and B is False.

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Then...

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$A \implies \neg B$

wraith daggerBOT
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Reborn

maiden dune
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If you're saying...

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$x < 5 \implies x \le 5$

wraith daggerBOT
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Reborn

maiden dune
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it is right.

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Because...

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$x \le 5$ means $x < 5$ (OR) $x = 5$

wraith daggerBOT
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Reborn

maiden dune
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Or, in more logical terms,...

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$x \le 5 \implies (x < 5) \lor (x = 5)$

wraith daggerBOT
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Reborn

maiden dune
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Notice that $x < 5 \implies x \le 5$ because $x < 5$ could mean $x < 5$ (True) [or] $x < 5$ could mean $x = 5$ (False)

wraith daggerBOT
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Reborn

cedar kilnBOT
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@split cave Has your question been resolved?

split cave
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so in implication A is always the first statement the if part and B is the last statement the conclusion correct?

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No matter how u turn it

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x<5 then x< or equal to 5

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here x<5 is A

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and x< or equal to 5 is B

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x or equal to 5 then x<5

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x or equal to 5 is A

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and x<5 is B

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correct?

cedar kilnBOT
#

@split cave Has your question been resolved?

cedar kilnBOT
#
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lament vector
cedar kilnBOT
lament vector
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Looking for help on this question

tropic oxide
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!status

cedar kilnBOT
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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 was told that it's wrong.
4. I got an answer and would like my work checked.
5. I have a question about someone else's work/solution.
6. I have completed the problem and don't need help anymore. Thank you.
7. None of the above
vital jay
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Well can you show c is a zero?

tropic oxide
vital jay
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Yeah fair enough

lament vector
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well it says I need to prove that -4 is a zero of c

vestal bluff
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how would you prove that

vital jay
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Yup, do you know how to do that?

lament vector
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long division

vital jay
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Well maybe, but there's a much much simpler way

lament vector
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Ik u can do synthetic but my teacher said she only wants long for our tests and homework

vital jay
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Well what does it mean for c to be a zero of P(x)?

lament vector
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That when we do long division with x-4 the remainder will be 0?

vital jay
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That's one interpretation, but it also means that P(c)=0

lament vector
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ok

vital jay
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Which is the same thing right? Because if P(x) is a multiple of (x-c), then since (c-c)=0 we must have P(c)=0

lament vector
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yea

vital jay
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So can you show c is a zero like that?

lament vector
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so do i do long division?

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cuz i also have to find the other zeros through factoring

vital jay
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Sure why not, I guess that'll be useful for the second part

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Yeah

lament vector
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ok ill try to set it up

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ok, now this is where i dont know where to start

vital jay
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Hmm I haven't tried explaining this topic before

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But you need to start by aligning with the largest term, right?

lament vector
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I believe I need a multiple to make x=x^3

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so x^2?

vital jay
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Yep

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Don't forget to apply x^2 to both terms btw, x^3 - 4x^2

lament vector
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so then

vital jay
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And what would be the remainder after subtracting x^3 - 4x^2?

lament vector
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-3x

vital jay
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Let me rephrase

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What would be the remainder of (x^3-3x^2-18x+40) - x^2(x-4) ?

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Because x^2 isn't what's left after factoring right? There's more steps to go

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Does that make sense at all?

lament vector
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Its not just the remainder of x^3-4x^2 and then we bring down the second term?

vital jay
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Not really, also x^3 - 4x^2 does not equal -3x

lament vector
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Oh

vital jay
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The exponents of x don't cancel with subtraction

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Here I'll just show you what I mean, gimme a second

lament vector
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Ok

vital jay
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So the "long" part of long division is that you need to repeat the previous steps until you're left with something smaller than x-4

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To find the next term you repeat the process with the result at the bottom there

lament vector
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So why do u bring down the 40 too, not just the 18x, repeat and then the 40?

upper ruin
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What kind of method have you been taught? 🤔

vital jay
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Well if you remember to bring down the 40 when you need to I guess you don't need it in the middle?

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But I like to keep things together whenever possible, since it's less likely for me to make a mistake by forgetting a term

lament vector
upper ruin
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Mmhh weird

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Have you a screenshot of that?

vital jay
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Also..........

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I just realized since c = -4 we should be using x+4, not x-4

lament vector
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Oh dam

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Perhaps I should ask my teacher what's going on then

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With her method

vital jay
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It shouldn't make much of a difference really

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Just different ways of presenting the same process

lament vector
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Oh ok

vital jay
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The term thing I mean

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x-4 and x+4 are very different and that needs to be corrected in our work

lament vector
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Ok

vital jay
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So can you show me the result of the first step with x+4?

lament vector
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Kk one sec

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Now I'm not sure where to go

lone slate
vital jay
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Yeah, you've essentially got x^3 - x^3 and -3x^2 - 4x^2, how do those two things resolve?

lament vector
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Im not sure

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So the x^3 cancels out

vital jay
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Yep!

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For the -3x^2 - 4x^2, you can pull out the x^2 part like this -3x^2 - 4x^2 = (-3 - 4)x^2

lament vector
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So then it's-7x^2?

vital jay
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Yep!

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So can you use that to set up the next step?

lament vector
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Is this the set up

vital jay
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Close, you don't need that extra minus sign out front

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Or

lament vector
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So this

vital jay
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Yup!

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Now I see you've already put 7x up at the top

lament vector
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Yea 7x^2

vital jay
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Actually it would just be 7x, no square

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Because just like we had x^2 to make the x match x^3, we need -7x to make x match -7x^2

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Like we did x^2(x+4) = x^3 + 4x^2

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So now we do -7x(x+4) = -7x^2 + ...

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Does that make sense at all?

lament vector
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Ohhhhhh

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Cuz we have to make x = 7x^2

vital jay
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Yep!

lament vector
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Ok so I brought 18x down now what

vital jay
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What is -7x(x+4)?

lament vector
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-7x^2+27x

vital jay
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Hmm, two things. The second term there should be negative right? And 27 is close but not quite right

lament vector
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-28

vital jay
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Ye

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So now you do (-7x^2-18x) - (-7x^2-28x)

lament vector
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10x?

vital jay
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Yup!

lament vector
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Here's where I am at

vital jay
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Looks good!

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I see in your answer you've put 10x, which is the right idea but you actually just want 10

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Because 10 times (x+4) will give you a 10x term, right?

lament vector
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Yesyesyes

vital jay
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Just like how we put 7x instead of 7x^2

lament vector
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Yea

vital jay
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Can you finish this off then? All that remains is to show that there's no remainder

lament vector
vital jay
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Yup!

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So can you tell me what the result of the division would be? For the sake of finding the other zeros

lament vector
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Now I gotta factor further