#help-13

1 messages · Page 70 of 1

errant vector
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alr

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lets solve for y'

ember lichen
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a;thpigh

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i think u made a mistake

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  • y
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not + y

errant vector
#

ye

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sorry lol

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its late

ember lichen
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all good

errant vector
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anyways im gonna move y and 2x to the other side ig

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-xy' + 6yy' = y - 2x

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and factor the y'

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y'(-x + 6y) = y - 2x

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if i make any silly mistakes point them out ig

ember lichen
#

makes sense

errant vector
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so ig you were right

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or symb was right

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y' = (y-2x)/(-x + 6y)

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i was confused cuz it was missing the y'

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y' = (y-2x)/(-x + 6y) = 1

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alright well this is a problem

ember lichen
#

why are we making y' = 0?

errant vector
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1

ember lichen
#

should've we make it 1?

errant vector
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sorry

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yeah

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lol

ember lichen
#

then i assume we just multiply the denom. out, yeah?

errant vector
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im not sure if we're meant to solve this or not

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there are 2 variables

ember lichen
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yeah

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that's what im confused about

errant vector
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it does say "any" tangent

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so like

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it might just want us to leave the point it touches untouched

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wait but that wouldnt make any sense cuz the problem would be too easy 😭

ember lichen
errant vector
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ok wait

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alr so the slope is 1

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and the points are (-12,f(-12)) and (12,f(12))

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im confused on how we were supposed to figure out 12,-12

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i look stupid

ember lichen
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no ur not

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i don't get it either

errant vector
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hmm

ember lichen
errant vector
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ima ask alpha

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wolfram alpha doesnt know

undone star
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im not too caught up with all the convo

ember lichen
#

you know it's fucked up when alpha doesn't know

undone star
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but from a glance

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it should be implicit?

ember lichen
#

yes

errant vector
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yeah

ember lichen
#

we alr did that

undone star
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so ur ifnal answer should be in terms of y' and y

ember lichen
#

this question is fucked up and i have like 10 more like these

errant vector
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basically, what values of x make y' = 1

ember lichen
errant vector
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except its implicit

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like so

ember lichen
#

wait

errant vector
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f(x,y) = 0

ember lichen
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dy/dx = 1
dy/dx = that stupid equation

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sub in 1

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solve for y

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then substitute it in

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into the original equation

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no?

errant vector
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stupid equation = 1

ember lichen
#

no the stupid f'(x)

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stupid equation

errant vector
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(y-2x)/(-x + 6y) = 1

ember lichen
#

yes

errant vector
#

ye

ember lichen
#

i got y = -x/5

undone star
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thats straonge

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i got negative 3x/5

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i might have done something wrong

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give me a sec, i do it on paper

ember lichen
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nah i checked it on desmos

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it's -x/5

errant vector
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alr

ember lichen
#

that is like our derivative

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wait no

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it's the uh

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what the fuck is it

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tangent?

errant vector
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thats another elliptical

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ellipsis

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whatever they're called

ember lichen
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yeah

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i got it mapped in desmos

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and uh

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it's an equation

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OH

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WE HAVE THE TANGENT

errant vector
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defined in terms of x and y

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f(x,y)

ember lichen
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SO WE SOLVE FOR INTERSECTIONS OF THE TANGENT

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ON THE ECLIPSE

errant vector
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OH

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I SEE IT

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BRUH

ember lichen
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this is fucked up

errant vector
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How was anyone supposed to know that

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what is this

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precalc?

ember lichen
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IB math calc + vectors

errant vector
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ib math?

ember lichen
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AP but for europeans, but i live in canada so they colonized us

errant vector
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ah

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vectors 💀

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that is a damn good problem but i hope i never see it on a test

ember lichen
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LMAOOO

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my teacher

errant vector
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😭 why was that so hard

ember lichen
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has like 10 more lined up

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nah it's not that

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it's cuz he is makes math contests 💀

errant vector
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i still dont understand how we were supposed to figure it out w/o a graphing calculator

ember lichen
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so bro will throw us the most diabolical problem known to man

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ok so uh

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-x/5

errant vector
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why would it have been the intersections tho

ember lichen
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idfk either

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i gotten so used to this

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i don't even wanna know anymore

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we got the normal?

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yeah the normal i think

errant vector
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nah

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the angle is 90deg

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isnt*

ember lichen
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true

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idfk then

errant vector
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😭

ember lichen
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LMAOOOO (i cant take this any longer with math. why did we invent this shit bro. im going back to the babylonian times not to warn them of god's warth, but to sabatoge their progress in math and return us back to cave men)

errant vector
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lmfao

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alr ig .done

ember lichen
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ok funny oart

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i dont know what to actually do

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so like

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so we take -x/5

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and sub it in?

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or like

errant vector
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nah

ember lichen
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do we make it equal?

errant vector
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we just graph -x/5

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and then the we get the (x,y) of the intercepts

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and then we plug it in for yk

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a

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dy/dx = 1

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is basically

ember lichen
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😭

errant vector
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f_2(x,y) = 1

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because 2 vars:x,y

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and then we take the intersections from -x/5 and plug em into f_2(x,y)

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wait this is getting so confusing one sec ima latex it

ember lichen
#

what?

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f_2?

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what is f_2?

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-x/5?

errant vector
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$$\frac{y-2x}{6y-x} = 1 \to y = -x/5$$

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wait

wraith daggerBOT
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amukh1

ember lichen
#

si

errant vector
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f(x) is the original function x^2 - xy..

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$$f(x) = -x/5 \to (a,b),(c,d)$$

wraith daggerBOT
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amukh1

errant vector
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ab,cd are the two coordinates we get from the intersection

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so we make it equal instead of substituting

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so therefore,

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$$f(x) = -x/5 \to (a,b),(c,d) \implies \frac{(b,d) - 2(a,c)}{6(b,d) - (a,c)} = 1$$

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alright there

wraith daggerBOT
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amukh1

errant vector
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see

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we get ab,cd

ember lichen
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where did uh

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2 and 6

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come from?

errant vector
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and they satisfy the equation

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from dy/dx

ember lichen
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ohhh

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alr

errant vector
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y - 2x / 6y - x

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im saying (b,d)

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cuz there are 2 y values, b and d

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cuz 2 intersections

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so now we solved that equation

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we can say

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f(k) + (x-k)

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where k is

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(a,c)

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wait sh-

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alright there

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thats my solution

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still confused on why its the intersection but whatever

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get it? kinda? lol

ember lichen
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but how would you be a,b and c,d?

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see i did make it equal

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i just an uglier

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x^3 equation

errant vector
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¯_(ツ)_/¯

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idk

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i cant scroll that far back rn

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to see

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but ill assume your right

ember lichen
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wait

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im stupid

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gahh

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it still doesn't solve shit

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i think we gotta subtitute in

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so we don't have to deal with a y

errant vector
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its solved

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no look

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if we set them equal

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we should be able to produce two ordered pairs

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one sec gotta get the question again

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$$

ember lichen
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i do that right

errant vector
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ohh

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fuck

ember lichen
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$$
5x^2 - 5xy + 15y^2 - 5 \cdot 132 - x = 0
$$

wraith daggerBOT
#

dannylewastaken

errant vector
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its not an explicit equation

ember lichen
#

i think we sub in

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then solve

errant vector
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wait im slowly getting more confused 😭

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we're solving for the intersections rn right

ember lichen
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yes

errant vector
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alr yeah however you prefer it should work

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mine doesnt work cuz thats not explicit

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i forgot ig

ember lichen
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BOOM

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SOLVED IT

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HOLY FUCK

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yeah

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you sub in y as -x/5

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then make those 2 equations equal

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then solve

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then it's just quadratic

errant vector
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wow

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thats amazing

errant vector
ember lichen
#

-x/5

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then the original

errant vector
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-x/5 = the original subbed y -> -x/5?

ember lichen
#

yes

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oh wait

errant vector
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and it gives the intersections?

ember lichen
#

i am dumb

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LMAOOO

errant vector
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nice notes

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you take those online? or on paper

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it looks online but the handwriting is too good for online

ember lichen
#

it's online

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i have an ipad

errant vector
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ah

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what app are the notes on?

ember lichen
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goodnotes

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OH WAIT

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I FORGOR

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THE MULTIPLY

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5*132

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LMAOOO

errant vector
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oh lol

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do you have the apple pencil or smthn else

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i used to use goodnotes but the notes didnt come out very well

ember lichen
#

veyg

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it's wrong

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im gonna

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die

errant vector
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😭

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atleast we somewhat figured it out

ember lichen
#

did i sub in wrong?

errant vector
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we just cant find the roots lol

ember lichen
#

we spent

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over 1 hour

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on this shit

errant vector
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bruhh

ember lichen
#

the next problem

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is worse 💀

errant vector
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😭

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can i see it

ember lichen
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WAITY

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IT EASIER

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WHAT

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HOW

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THIS IS SO MUCH EASIER

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WHY THE FUCK

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OH MY GOD

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IM GONNA KMS

errant vector
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lmfao

ember lichen
#

THIS IS LITERALLY DERIVE

errant vector
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and plug

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thats it

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lmfao

ember lichen
#

THEN PUT IT INTO THAT STUPID Y_1 - Y_2 = SLOPE(X - X_1)

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BRI

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BRO

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WHY

errant vector
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6(x-3) -2

ember lichen
#

life is unfair

errant vector
#

there

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that should be it unless im tripping

ember lichen
#

yeah

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ur right

errant vector
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ig u coulda done that too lol

ember lichen
#

nah i have to my teacher is persistent on that

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but gahh

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how to find roots

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bruh

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did i sub it in wrong?

errant vector
#

im not sure

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:google:

ember lichen
#

i-

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line 2

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LMAOO

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i moved it over

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and din't change the sign

errant vector
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TF

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THEY DIDNT TELL ANYONE ACTUALLY HOW TO SOLVE

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NOO

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oh wait

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maybe you set both equations to 0

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and then set them equal to eachother??

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ohhh i think thats it

ember lichen
#

what 😭

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setting it to zero

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is just x = 0

errant vector
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lemme just do it in my notebook and send a pic

ember lichen
#

well you should get

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x = +- 10

errant vector
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oh wait no

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im so f- confused

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how does one find the intersections between an implicit function and an explicit function

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so y = -x/5

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-y - (x/5) = 0

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right

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and x^2 - xy + 3y^2 - 132 = 0

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so -y - (x/5) = x^2 - xy + 3y^2 - 132

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😭😭 i hope this is right

ember lichen
#

wait

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-y - (x/5) ?

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OHH

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you moved it

errant vector
#

ye

ember lichen
#

oh

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that makes more sense...?

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wait no

errant vector
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i set them = 0

ember lichen
#

how do you even

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solve it

errant vector
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so they are equal to eachother

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yeah thats the part idk..

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lol

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WHYY

ember lichen
#

bro you gotta sub in y

errant vector
#

i think i might go into spiraling depression

ember lichen
#

dawg im getting so close to x

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its making me go insane

errant vector
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lol

ember lichen
#

it's x = 9.7 and -10.1

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💀

errant vector
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wow thats like .3 and .1 off

ember lichen
#

yeah

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clearly i am going insane

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the more i stare at this proble,

errant vector
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its been way more than an hour at this point 😭 — Today at 12:45 AM

ember lichen
#

the more i want to

errant vector
#

like 15 mins

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ig thats not alot more

ember lichen
#

question if wanting a cs degree is worth it

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i could move to the netherlands

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and get a game dev degree and actually have fun

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but no i choose to stay and suffer

errant vector
ember lichen
#

bro also wants to suffer too

errant vector
#

yeah lol

ember lichen
#

bro this is messed up

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i can't solve for x

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bro what??

errant vector
#

this problem is too much

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ask your teacher abt it im actually curious as hell how thats supposed to even fing be solved

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like tf

ember lichen
#

amukh

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you are a genius

#

albert if you will

errant vector
#

:0

ember lichen
#

no wait

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you were almost albert

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yeah you set both to zero

errant vector
#

LOL takes it back

ember lichen
#

but never had to

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it was literally

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i shit you not

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sub in

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and solve

errant vector
#

for what

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x?

ember lichen
#

y

errant vector
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im dead inside

ember lichen
#

take the orignial equation

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replace y wiith -x/5

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im gonna

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die

errant vector
#

😭

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my mind is too young for this pain

ember lichen
#

maybe the hood isn't that bad

errant vector
#

lol

ember lichen
#

nowait

#

we arent done yet

#

we need to uh

#

equation

#

that is easier though

errant vector
#

are u using an apple pencil?

ember lichen
#

yeah

errant vector
#

damn

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wait i was gonna get one and i stopped after i saw it was 129 bucks 😭

ember lichen
#

LMAOO

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it's worth it imo

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like papers no more

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and like its cool as shit since funny questions like these

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ill put them into my note taking app

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and make a note for myself to remember

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that this is how i solve this question

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oh my god

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i finished solving it

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oh my god

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i don't feel happy

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i just am

#

zamn so this is what the buddha meant when he said attachment meant suffering. thank you @errant vector for helping me through this experience

#

.close

cedar kilnBOT
#
Channel closed

Closed by @ember lichen

Use .reopen if this was a mistake.

#
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Remember:
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silent plover
cedar kilnBOT
silent plover
#

hi can someone help me for case 2

flint plinth
silent plover
#

ah

#

i got it

#

ty

cedar kilnBOT
#

@silent plover Has your question been resolved?

#
Channel closed

Closed by @silent plover

Use .reopen if this was a mistake.

cedar kilnBOT
#
Available help channel!

Send your question here to claim the channel.

Remember:
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>.
• Type the command .close to free the channel when you're done.
• Be polite and have a nice day!

Read #❓how-to-get-help for further information on how to ask a good question, and about conduct in the question channels.

quartz dome
#

how do i find the domain and range

cedar kilnBOT
south tundra
#

So we must have 3 - 2x - x^2 >= 0

#

But, also,

#

A fraction exists as long as its denominator is nonzero

#

Meaning we can't have 3 - 2x - x^2 = 0

quartz dome
#

i waited so long that i figured it out nearly

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i got up to having (x-1)(x-3) root under the 1

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so the domain should be x can not be equal to 3 and 1

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but the answer says its −3 < x < 1

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can u explain how they got that

#

typo oops

south tundra
#

You had (x - 1)(x - 3) < 0, right?

quartz dome
#

yes

south tundra
#

Hm, wait though

#

Could you show your work?

quartz dome
#

sure

#

which part?

south tundra
#

The thing is that you should have started 3 - 2x - x^2 > 0

#

Which is equivalent to (x - 1)(x + 3) < 0 instead

quartz dome
#

wait then lemme check i think i messed up

#

This is my working

quartz dome
south tundra
# quartz dome

From there you factor the last inequality into (-3 - x)(x - 1) > 0, right?

#

Here you can multiply both sides by -1, which flips the sign

#

Hence the (x + 3)(x - 1) < 0

quartz dome
#

ohh alr

#

why is it −3 < x instead of x < -3

south tundra
#

Let's say x < -3

#

Then x + 3 is negative, right?

quartz dome
#

oh yeah

south tundra
#

And so is x - 1

#

And the product of two negative numbers gives a positive number

south tundra
#

There is an intuitive and a formal way to solve this equation

#

You can imagine the graph of the parabola (x + 3)(x - 1)

#

(Or sketch it)

#

It should look like this

#

,w graph y = (x + 3)(x - 1)

wraith daggerBOT
south tundra
#

Doesn't matter how accurately you draw/imagine it, the important thing to remember is that it passes the x-axis at -3 and 1

#

And that the parabola is directed upwards

south tundra
#

So, we need to look at the part where parabola goes below the x-axis

quartz dome
#

jyes

south tundra
#

As you can see, that happens when x is between -3 and 1

#

So the solution is -3 < x < 1

quartz dome
#

oh lol i get it

quartz dome
#

nvm got it

#

ty

#

and for range do i just sub in some stuff?

south tundra
#

For the range you first need to know what values does the quadratic expression take

#

In order to do that, we must know the maximum/minimum (in this case, minimum) value of the parabola

#

That can be done in two ways:

  1. Complete the square
  2. Plug in x = -b/2a into the expression (a being the coefficient of x^2 and b being the coefficient of x)
#

Here it is simpler to complete the square

#

Cause x^2 + 2x - 3 is clearly (x + 1)^2 - 4

#

Can you guess the minimum value of this?

quartz dome
#

did u get x^2 + 2x - 3 from multiplying by -1

#

and is the minimum (-1, and something)

south tundra
#

Good note though, we needed to know the maximum of 3 - 2x - x^2 instead whoops

#

But its maximum is equal to the -minimum of (x + 3)(x - 1)

quartz dome
#

oh ok

south tundra
#

Okay, let me redo this part if you are confused

quartz dome
#

thanks

south tundra
#

We need to know the maximum value of 3 - 2x - x^2

#

We can complete the square in order to do that

quartz dome
#

yes

south tundra
#

3 - 2x - x^2 = 3 + 1 - 1 - 2x - x^2 = 4 - (x + 1)^2

quartz dome
#

do we need to know the minimum

#

oh was that what u were doing earlier

south tundra
#

Yes

quartz dome
#

mb

south tundra
#

So we have shown that 0 < 3 - 2x - x^2 <= 4, right?

#

(0 < because we are picking the values for which the quadratic expression is positive)

south tundra
quartz dome
#

where did the <= come from

#

<= 4

south tundra
#

<= 4 is the same as saying 4 is the maximum value of that

#

And we have shown that 4 is exactly that

#

So 3 - 2x - x^2 <= 4

quartz dome
#

oh ok

south tundra
#

3 - 2x - x^2 <= 4 and therefore sqrt(3 - 2x - x^2) <= 2, right?

quartz dome
#

yes

south tundra
#

And 1/sqrt(3 - 2x - x^2) >= 1/2

#

So, the range is [1/2, +inf)

quartz dome
#

what happened in between that

south tundra
quartz dome
south tundra
#

Yeah you can do that generally

quartz dome
south tundra
#

Flipping the fraction changes the inequality sign

#

Oh

#

You mean that

#

We wanted to know the range of 1/sqrt(3 - 2x - x^2), right?

#

Aka the set of values that it could take

#

And we have shown that 1/sqrt(3 - 2x - x^2) is always bigger than or equal to 1/2

#

So it takes every value from 1/2 and further

quartz dome
#

yes i understand

south tundra
#

So the set of its values is simply [1/2, +inf)

quartz dome
#

the answer page says the answer was y > 12

#

is that the same thing?

south tundra
#

I have look at the graph of our function a while ago and confirmed that the range is actually [1/2, +inf)

#

So the answer page is wrong catshrug

#

,w graph 1/sqrt(3 - 2x - x^2)

wraith daggerBOT
south tundra
#

See, the graph goes from 1/2 upwards

quartz dome
#

i dont get it but ill trust u on that ig

#

maths is hard imma read over this

#

ty for helping

#

.close

cedar kilnBOT
#
Channel closed

Closed by @quartz dome

Use .reopen if this was a mistake.

#
Available help channel!

Send your question here to claim the channel.

Remember:
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>.
• Type the command .close to free the channel when you're done.
• Be polite and have a nice day!

Read #❓how-to-get-help for further information on how to ask a good question, and about conduct in the question channels.

proven silo
#

hi

cedar kilnBOT
proven silo
#

how to prove if the angle suspened by the arc is equal to the double of it in any part of circle

livid hound
#

prove if the angle suspened by the arc is
you mean central angle?

#

you can look up proofs of it

#

proof of inscribed angle theorem

dusk finch
proven silo
#

.close

cedar kilnBOT
#
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signal flame
#

i am lost on the one with 0,5 😇

cedar kilnBOT
tropic oxide
#

do you mean to say, "I know how to solve direct proportion problems like this, but the presence of the number 0.5 paralyzes me"?

signal flame
#

well i’m just lost on how to find out B below the 0,5th

vagrant elbow
signal flame
#

nope

vagrant elbow
#

Do you know how these problems work

signal flame
#

not sure nameitpls

vagrant elbow
#

Alright

#

What does it mean for a and b to be directly proportional?

cedar kilnBOT
#

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silver sphinx
#

help plz

cedar kilnBOT
south tundra
#

Have you tried anything?

strange wind
# silver sphinx help plz

determining the nature is basically if is a max or minimum point, which can be shown by d2y/dx2 being negative or positive
Sketch should be fine

silver sphinx
#

idk what do i do for x^3(x-4)

south tundra
#

It is asking you to find the stationary points of the curve y = x^3(x - 4) and determine their nature

silver sphinx
#

like i did 3x(x-4)

livid hound
#

3x(x-4)
where's that coming from

south tundra
#

Meaning you need to find the points where the derivative of x^3(x - 4) is 0

silver sphinx
#

yeah

silver sphinx
livid hound
#

no

silver sphinx
#

i think?

livid hound
#

y = x^3(x-4)

crimson sedge
#

Can you differentiate this expression?

south tundra
#

To find the derivative you can use the product and power rules

#

Or expand the brackets and just use the power rule

#

Anyways, you should get that dy/dx = 4x^3 - 12x^2

#

Finding the zeroes of this should be simple

silver sphinx
#

okay so

#

it should be

#

3x^2+(x-4)3x^2

#

or no

silver sphinx
south tundra
#

y = x^3(x - 4) = x^4 - 4x^3

#

dy/dx = 4x^3 - 12x^2

cerulean sail
silver sphinx
south tundra
#

Applying the product rule right away should have yielded 3x^2(x - 4) + x^3

silver sphinx
#

oh okay

cerulean sail
#

[you differentiated both x^3 and (x-4) for that first term, it looks like]

south tundra
silver sphinx
south tundra
#

So, can you find the zeroes of dy/dx?

silver sphinx
#

wdym zeroes

south tundra
#

The values of x for which dy/dx = 0

silver sphinx
#

so x=0

south tundra
#

No

#

4x^3 - 12x^2 = 0

#

Generally a number c is a zero of a function f if and only if f(c) = 0

silver sphinx
#

okay

south tundra
#

So by the zeroes of dy/dx I mean the solutions to 4x^3 - 12x^2 = 0

#

(Since dy/dx and 4x^3 - 12x^2 are the same as we have shown)

silver sphinx
#

so x=3

south tundra
silver sphinx
#

x=0 and x=3

#

right?

south tundra
#

Yeah

#

So x = 0 and x = 3 are the stationary points

#

Now, it is also asking you to "determine their nature"

#

That means "Determine whether they are the maximum/minimum/saddle points"

#

We can do that by looking at the sign of y'' at those points

#

Can you find the expression for y''?

silver sphinx
#

y=0 and

#

y=-27

#

so (0,0) and (3,-27)

south tundra
#

Right, those are the stationary points

silver sphinx
#

but if i do d^2y/dx^2

south tundra
#

Now we need to know the signs of y'' at x = 0 and x = 3

silver sphinx
#

when x=0 d^2y/dx^2=0

silver sphinx
south tundra
#

y''*

south tundra
south tundra
silver sphinx
#

so 0 and positive

south tundra
#

Now check d^2y/dx^2 for x = 3

silver sphinx
#

36

#

so it's a min pt (3,-27)

south tundra
#

Yeah

silver sphinx
#

okay

#

like this right

south tundra
#

Yeah

cedar kilnBOT
#

@silver sphinx Has your question been resolved?

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wild kindle
#

The rectangle HDEG has the same area as the square ABFG.
In addition, the lengths DE = 12 cm and GE = 27 cm are given. Calculate the
Size of the hatched area ABFH.

wild kindle
#

The rectangle HDEG has the same area as the square ABFG.
In addition, the lengths DE = 12 cm and GE = 27 cm are given. Calculate the
Size of the hatched area ABFH.

cedar kilnBOT
#

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#

@wild kindle Has your question been resolved?

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graceful gyro
cedar kilnBOT
graceful gyro
#

Why can't I find the voltage through capacitors when s is closed

#

They are in series so

scarlet garnet
#

,rccw

wraith daggerBOT
graceful gyro
#

2× 9 = 18

#

Cause total charge could be find by eff C and V right ???

#

<@&286206848099549185>

clear berry
#

Can't help you with physics problems

cedar kilnBOT
#

@graceful gyro Has your question been resolved?

cedar kilnBOT
#

@graceful gyro Has your question been resolved?

cedar kilnBOT
#

@graceful gyro Has your question been resolved?

gritty galleon
# wraith dagger

I feel I should be ablle to do this but i cant help, sorry 😦

distant cedar
#

Hi @graceful gyro

#

Where are you facing issues? This is a physics problem btw not maths

cedar kilnBOT
#
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pale badger
cedar kilnBOT
pale badger
#

Sorry 1 sec

crimson sedge
#

Send a picture. People won’t download files

pale badger
#

Can someone explain to me question 6 (c) (iii)

pale badger
cerulean sail
#

Did you manage part ii, by any chance?

pale badger
pale badger
pale badger
#

But i dont understand how they turned (cos2x+1/2)^2 into zero?

cerulean sail
#

Any real number squared is nonnegative, in particular, $\pqty{\cos(2x) + \frac{1}{2}}^{2} \geq 0$

wraith daggerBOT
#

@cerulean sail

pale badger
#

Oh shit yeah

#

Alri thanks

#

Feel stupid now lol

cerulean sail
#

It happens sometimes, don't worry catlove

pale badger
#

.close

cedar kilnBOT
#
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ebon badge
#

can someone help me?

#

i translated it so and i dont really know math words in english

cedar kilnBOT
#
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ebon badge
cedar kilnBOT
ebon badge
#

a is a parameter it has 1 value

#

i translated the question and i dont know any math terms in english

cedar kilnBOT
#

@ebon badge Has your question been resolved?

cedar kilnBOT
#

@ebon badge Has your question been resolved?

cedar kilnBOT
#
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eternal dagger
#

could someone help me with this practice problem please?
i think its a combination question but im unsure how to solve it

cedar kilnBOT
#

@eternal dagger Has your question been resolved?

ebon badge
#

.reopen

#

wow man why did you have do that

#

thats just an annoying thing to do

eternal dagger
#

my bad?

ebon badge
#

what grade are you in?

eternal dagger
eternal dagger
ebon badge
#

thats in collage?

#

what?

#

how?

#

did you already learn the stuff i asked for help for?

eternal dagger
#

probably but i forgot it

#

ill leave the channel

#

i thought ur question had been resolved

ebon badge
#

btw i solved your problem

#

the percentage of left handed kids is 11.1%

#

the percentage of boys is 55.5%

#

and the rest just subtract from 100

eternal dagger
#

ok thanks

#

.close

cedar kilnBOT
#
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ebon badge
cedar kilnBOT
#
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strange wind
cedar kilnBOT
strange wind
#

i dont know how to approach this problem

#

the far i have gotten is
For x0 = 0, we have x1 = 1, x2 = 2, x3 = 5, x4 = 26, x5 = 677, x6 = 458330, x7 = 210066388901, x8 = 441875919508520019

cedar kilnBOT
#

@strange wind Has your question been resolved?

crimson delta
#

do you know what modulo is?

strange wind
#

not really, is it the same as modulus?

#

|this|

crimson delta
#

no

strange wind
#

uhm could you explain it? or connect it tho this question?

#

wait @ebon badge was this your channel?

ebon badge
#

im just interested what grade do you think should learn this?

#

yes

crimson delta
#

well it was but now its not anymore

strange wind
#

sorry man

ebon badge
#

oh ok

strange wind
#

ill leave from here share your question again

ebon badge
#

can you help me with my question

strange wind
#

lol lemme check it out

crimson delta
#

barney get a new channel

ebon badge
strange wind
#

@crimson delta ill ping you to my new channel its fine

crimson delta
#

this is your channel

#

dont leave

strange wind
#

ohh

#

okay

#

For x0 = 0, we have x1 = 1, x2 = 2, x3 = 5, x4 = 26, x5 = 677, x6 = 458330, x7 = 210066388901, x8 = 441875919508520019

#

thats where we were

crimson delta
#

it will take a bit longer to explain modulo so I'm currently thinking about how to do this without it

strange wind
#

okay sure, ill be waiting its fine

#

some of the ideas that i had was proof by induction

crimson delta
#

hmm I can't think of anything

#

so the idea about modulo that the only thing that matters is remainders

#

we want to show that eventually x_k - 2 is divisible by 30, so phrased differently, eventually it has remainder 0 after dividing by 30

#

which happens when x_k has remainder 2 when divided by 30

#

now the nice thing about remainders is that they play nice with addition and multiplication

#

namely, if a has remainder r and b has remainder q, then ab has the same remainder as rq and a+b has the same remainder as r+q

#

this makes the numbers you have to handle much smaller

#

for example, x5=677 in your example has remainder 17 and x6=458330 has remainder 20

#

and now notice that if you instead just work with the remainders, then 17^2+1=290 also has remainder 20

strange wind
#

wait but working with remainders wount prove that its divisible by 30

#

like x5=677 we know is not a multiple of 30

crimson delta
#

yes it has remainder 17

#

but if the remainder of x_k is 2, then x_k-2 is divisible by 30

#

and that's what you want to show

strange wind
#

ohh yeah, basically is the remainder is any prime factor of 30 we have our answer right?

crimson delta
#

no

#

btw you made a mistake when calculating x8

#

,calc 210066388901^2+1

wraith daggerBOT
#

Result:

4.4127887745906e+22
crimson delta
#

..

#

44127887745906175987802

strange wind
#

ohh lemme do it again

strange wind
#

thats the one

crimson delta
#

which you might notice is in fact 2 above a multiple of 30

#

but the nice thing here is that we could have noticed that easier by just working with the remainders

#

20^2+1=401 has remainder 11

#

and then 11^2+1=122 has remainder 2

#

(and that's how I noticed you made the mistake in the first place)

strange wind
#

tho the only problem here is that we need to prove for all possible values of x0

crimson delta
#

or do we only have to prove it for all possible remainders that x0 could have

strange wind
#

i mean yes, thats one way of putting it

#

but with the remainder approach what proof do we use?

#

like how can i prove this?

crimson delta
#

bruteforce

#

I can't think of anything nicer right now

strange wind
#

i am doing this on paper, how do i plan to brute force on this

crimson delta
#

well its only 30 possible remaindeers

#

like with your earlier sequence you started with the remainder 0 and then got 1, 2 (at here you would be done btw), 5, 26, 17, 20, 11, 2

#

which shows that if x0 has any of those then eventually you reach a 2

strange wind
#

dont you think there could be another way, coz i mean 30 possibilities is quite a number to do by hand

#

if i was using a program/python to do it, thats fine

crimson delta
#

well you will notice that because you are working with squaring then a lot of values fall together

#

(essentially for the reason that x^2=(-x)^2)

strange wind
#

well before i start with the whole bruteforce, do you think there is a easier way

#

something like using sum of a series or something in those lines?

crimson delta
#

no I can't think of anything

pastel path
#

So say like there was an equation 4x+5y<=180
how do i calculate x and y so that their sum is the greatest combination (of whole numbers)

#

i dont know if this channel is empty but it doesnt say a name haha

strange wind
#

@pastel path

#

its not empty sorry

pastel path
#

mk my bad.

#

thanks for letting me know!

strange wind
#

np mate

strange wind
strange wind
#

.close

cedar kilnBOT
#
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livid crescent
#

does this math look correct

cedar kilnBOT
#

@livid crescent Has your question been resolved?

dire geode
cedar kilnBOT
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scenic fable
#

I dont understand

cedar kilnBOT
scenic fable
#

sad moment

high spruce
#

:(

scenic fable
#

I tried to understand

#

but I cant

#

I want to learn math

#

and english

#

sad

#

very sad

#

pls tell me advice

high spruce
#

what's your question

scenic fable
#

my book is in english

#

and is math

#

In a meeting there are 201 people of 5 different nationalities. It is known that, in every group of 6, at least two are the same age. Prove that there are at least 5 people from the same country, of the same age and of the same sex.

high spruce
#

ok this is pigeon hole principle

#

are you familiar with it?

scenic fable
#

noyt

#

I can help with math exercise

#

or not

#

my dear acquaintace

#

tance

high spruce
#

basically, the pigeon hole principle means that if there are n+1 holes and n pigeons then one of the holes will have at least 2 pigeons

#

so by this logic, at least 41 people will have the same nationality, and at least 101 people will have the same sex

#

I'm trying to figure out the age condition though, give me a minute

scenic fable
#

I dont understand

#

because I dont speak english

high spruce
#

what language do you speak

scenic fable
#

spanish

#

but normally

high spruce
#

hablo

scenic fable
#

can you speak in englih

#

i learn english and math

#

bruh

high spruce
#

bruh

scenic fable
#

whay

#

what is bruh

high spruce
#

brah are you trolling

#

ok anyway

scenic fable
#

not

high spruce
#

so let me try and clarify the quetsion

#

there are 201 people
that means at least 101 are of one sex

#

is that clear?

high spruce
scenic fable
#

use trasladertor google

#

is very bad

high spruce
#

?

#

Entiendo espanol mi amigo

high spruce
scenic fable
#

I want to learn english

#

math not

#

when i have a ask of math

#

i go to her

#

here

high spruce
#

I'm trying to teach you maths

#

this isn't an english learning discord

cedar kilnBOT
#

@scenic fable Has your question been resolved?

cedar kilnBOT
#
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dusty ibex
#

am I trippin or isnt all of these wrong?

cedar kilnBOT
gritty viper
#

you're tripping

dusty ibex
#

can you show me how to work these out?

#

i substitube 1 first into the formula on the right side then i do 2 then 3

gritty viper
#

well I mean one thing you could do is try to find a counterexample to one

gritty viper
#

well 3 of them should be true, one isn't right

#

So if you find an n value that doesn't work you know that's the false one

dusty ibex
#

take number 1 for example

#

i say 2(2+1) that is 6

#

I dont think that is what i should get eithere

gritty viper
#

?

high spruce
#

the first one can be easily derived using the formula for the sum of the first n integers

#

this guy

#

add the first and last, second and second to last, third and third to last and so on terms together

#

and from there you can derive formula

dusty ibex
#

like that?

autumn fox
wraith daggerBOT
#

Mikkel

high spruce
#

it's the same as what Mikkel is describing

#

just the 'simplest case' I guess

cedar kilnBOT
#

@dusty ibex Has your question been resolved?

cedar kilnBOT
#
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terse locust
#

Hello, I don’t know where to begin?

cedar kilnBOT
#

@terse locust Has your question been resolved?

zenith sail
#

@terse locust Don't worry about Sierra's simulation. Only one of your choices gets the true probability right anyway.

terse locust
zenith sail
#

consider all the possibilities when you roll a pair of dice

#

how many sum up to 7 or 11?

zenith sail
#

yep

terse locust
zenith sail
#

yep

terse locust
zenith sail
#

yep 👍

terse locust
zenith sail
#

np

terse locust
#

.close

cedar kilnBOT
#
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finite moth
cedar kilnBOT
finite moth
#

Hey, I'm having trouble with the idea of the inequality here in the induction step.

#

Obv we're assuming $3^n \geq 2^(n+1)$

wraith daggerBOT
#

Солдат удачи

finite moth
#

But with the inequality, couldn't I literally just multiply it by 3^n and $2^n) on either side

#

as 3^n preserves the inequality

#

and 2^n is established to be smaller than 3^n

finite moth
#

So, given it's an inequality $3^n * 3^n = 3^(n+1)$

wraith daggerBOT
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Солдат удачи

finite moth
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because we're trying to prove $3^(n+1) \geq 2^(n+2)$

wraith daggerBOT
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Солдат удачи

finite moth
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how do I make these non cancer exponents, whatever

finite moth
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How would I approach this problem then?

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The inequality aspect confuses me

dire geode
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3^n times 3^n equals 3^(2n)

finite moth
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How would you then get n+1, by adding them together?

dire geode
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3>2 works as well

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,tex .exp rules

wraith daggerBOT
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riemann

dire geode
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To get 3^(n+1), you use first row above with x=n

finite moth
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oh, so I would multiply by 3?

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$3^n * 3^1 (3) = 3^(n+1)$

wraith daggerBOT
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Солдат удачи

finite moth
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Okay, that makes sense.

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Can I do the same on the other side since it is an inequality and 3>2?

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but with 2

dire geode
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You'd chain the inequalities

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Something like 2^(n+1) * 2 < 3^n * 2 < ... < 3^(n+1)

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Maybe <= instead of <

finite moth
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I haven't seen it done like that before for this kind of inequality proof, I thought since it's strictly still less than the LHS adding something would work.

cedar kilnBOT
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@finite moth Has your question been resolved?

cedar kilnBOT
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