#help-27

1 messages · Page 110 of 1

native briar
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for -x^8cosx

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does it become

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-8x^7-sinx

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Or

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-8^7cosx

boreal karma
#

so it might be easier if we pretend like the negative isnt there for now

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and then just apply it at the end

native briar
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Ok

boreal karma
#

heres another way to write it that might make it simpler for you

native briar
#

wait so I’m confused now

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after we got rid of the 16

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what do we do now

boreal karma
#

-(x^8 d/dx (cosx) + (d/dx x^8) cosx)

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thats what you need to do to solve this problem

native briar
#

can you use the bot to type it

boreal karma
#

im new here and unfamiliar with the bot but ill write it out on paper

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understandable?

native briar
#

._.

boreal karma
#

okay basically what im saying is

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take the derivative of cosx and x^8

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then multiply the derivative of cosx by x^8, this is one term

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and multiply the derivative of x^8 by cosx, this is the other term

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the two terms are added to eachother and then we apply the negative sign from earlier

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also im sorry but i gotta leave for a class

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maybe you can ping a new helper since im struggling to explain it anyways

native briar
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hmm

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<@&286206848099549185>

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I'm still having issues understanding how to solve this problem

silver fjord
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What

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What do you have so far?

native briar
#

_> I can explain

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so far I have

silver fjord
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go ahead

native briar
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we replaced the theta sign with x

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and

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i did

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derivative of x^8

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which is 8x^7

tiny linden
#

You have to use product rule

native briar
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and derivative of cosx

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-sinx

silver fjord
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ok so far so good

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now how do you use those facts to get the answer

native briar
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no clue

silver fjord
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I'm sure you do

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you have $-x^8 \cos x$

woven radishBOT
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TooManyCooks

silver fjord
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you don't have them by themselves

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you have them multiplied together

native briar
#

yea

silver fjord
#

So what does that mean if you want the derivative

native briar
#

separate them?

silver fjord
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you already did that

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but there's a rule to use when you have two things multiplied together

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you used it repeatedly earlier

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allo?

native briar
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yea?

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sorry

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Is it product rule ?

silver fjord
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yes

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that's exactly it

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you separated them into x^8 and cos x

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now i want you to use the product rule to give me an answer

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you already told me the ingredients

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you just need to put them together

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if it helps, start by telling me what the product rule is

native briar
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it’s fxg = f’•g+g’•f

silver fjord
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(fg)', but yes that's it

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So now I want you to use that to calculate the derivative

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let's say f is x^8

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and g is cos x

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you don't have to give me the final answer. just tell me step-by-step what your solution is

native briar
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ok

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I got

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(f•g)’=(8x^7•cosx)+(x^8•-sinx)

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?

silver fjord
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close! but good progress

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you missed a minus sign on the second term

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remember (cos x)' = -sin x

native briar
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yea

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oh yea

silver fjord
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Got it?

native briar
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yes

silver fjord
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Ok

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Now, there's an overall minus sign in your problem

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Remember, it was $-x^8 \cos x$

native briar
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yea

woven radishBOT
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TooManyCooks

native briar
#

yes

silver fjord
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so you just bring that back by multiplying everything by minus sign

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So with that, what's your final answer?

native briar
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??

silver fjord
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you have a -1 multiplying your entire expression

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that's the minus sign in front

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I'm asking you to distribute it in your answer

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$-\left( 8 x^7 \cos x - x^8 \sin x \right)$

woven radishBOT
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TooManyCooks

native briar
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oh ok

silver fjord
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that's what you have right?

native briar
#

hm

silver fjord
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or no?

native briar
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Yea

silver fjord
#

You sure?

native briar
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Yea

silver fjord
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Ok good

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so now you just distribute that - sign

native briar
silver fjord
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you have 2 minus signs on the second term

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they should multiply each other

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you're missing that

native briar
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oh

silver fjord
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first term is correct

native briar
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ok

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So like this ?

silver fjord
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lol no

native briar
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_>

silver fjord
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you had the expression right

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you just didn't multiply it properly

native briar
#

o

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You mean this second one here

silver fjord
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Ok now you need to distribute the minus sign

native briar
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is it

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-8x^7•cosx+x^8•sinx?

silver fjord
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Yes!

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So which answer was that?

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Among the list

native briar
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hm

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is it

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2nd one?

silver fjord
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look carefully

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look at all of them

native briar
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hm

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oh

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last one

silver fjord
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yes

native briar
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yay

silver fjord
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gj

native briar
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tyty

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how would I solve this

silver fjord
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what do you think

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you had a similar problem before actually

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and i seem to recall you did that correctly

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so what do you think you should do here

tiny linden
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When you see that you have to find a derivative of a fraction what do you think you should do?

native briar
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cry

tiny linden
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Not after we teach you

native briar
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but

tiny linden
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You’ll be laughing with joy

tiny linden
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Because that’s what this company stands for

native briar
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i love ur enthusiasm

tiny linden
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Our pleasure

native briar
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ok

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so

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do I separate the fraction?

tiny linden
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Have you heard of the quotient rule?

native briar
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lord

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ur right

tiny linden
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I’ve heard this helps people memorize it

native briar
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Ok I got it

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Like this ?

tiny linden
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Exactly

native briar
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nice

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Is this right ?

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<@&286206848099549185>

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tiny linden
native briar
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.reopen

devout snowBOT
#

native briar
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No ?

tiny linden
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You need to distribute the 3x^2 to (x-1) to multiply the two

native briar
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How?

tiny linden
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When you bring x-1 to the numerator it has to be in parenthesis

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So it’s 3x^2 times x - 3x^2 times 1

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For the upper left parenthesis

ember pier
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f=√x+5 =x and f(a²)=aᵇ+c howwww

native briar
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??

ember pier
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do you know how

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how to find b and c

native briar
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I’m confused

ember pier
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Bro this my math teacher killin my ass

native briar
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what’s going on

ember pier
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how to find b-c

tiny linden
ember pier
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i believe we workin on cartesian diagram or sum

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but wth is thus

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this

native briar
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I’m lost

tiny linden
native briar
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Yep

tiny linden
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It’s supposed to be (3x^2 * (x-1))

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Minor difference but it changes the result, you have to distribute 3x^2

native briar
#

??

tiny linden
native briar
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no idea

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is it

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3x^2-3x^2?

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<@&286206848099549185>

junior bridge
#

Ill help you give me a second

native briar
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thx

junior bridge
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The solution for this equation is zero

native briar
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????

tiny linden
native briar
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This is the original question

tiny linden
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So then the numerator would be 3x^3-3x^2-x^3

native briar
#

Yea

native briar
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So is the answer

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2x^3-3x^2/(x-1)^2

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<@&286206848099549185>

silver fjord
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Oh what's up

native briar
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Am I right

main gull
native briar
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omggg hiii

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and thanks

main gull
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Well you need parentheses in the numerator when you write fractions in text form

native briar
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oYea sorry

silver fjord
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i member that

native briar
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wrong one

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Here we go

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I tried to separate the fraction by writing it as

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5x^2/5x+20x/5x

main gull
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Yeah now you can simplify it

native briar
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that’s where I’m stuck

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ok can you simplify 5x^2/5x as 5x?

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or does it simplify to 5x^2?

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@main gull

fleet eagle
native briar
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:0? Fr

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?

main gull
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x

native briar
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How?

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wait

main gull
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Because $\frac{5x^2}{5x}$ the gcf of the numerator and denominator is 5x

woven radishBOT
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dldh06

native briar
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is it bc 5x^2 simplifies to(5x*5x)

main gull
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5x^2 = 5 * x * x

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(5x * 5x) = (5x)^2

native briar
#

yea

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so is it

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x + 4x?

main gull
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No

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Because $\frac{20x}{5x} \neq 4x$

woven radishBOT
#

dldh06

main gull
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Notice how the x's are common and can be canceled out

tiny linden
main gull
tiny linden
native briar
#

so then

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what does 20x/5x simplify to

native briar
#

oh yea

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So

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yea idk

main gull
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What are you left when the x's get canceled out

native briar
#

20/5?

main gull
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Yes

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Now simplify 20/5

native briar
#

4/1?

main gull
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And that equals?

native briar
#

4?

main gull
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Yes

native briar
#

it simplifies to x+4?

main gull
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Yes

native briar
#

but it is that the derivative?

main gull
#

No

native briar
#

the derivative is 1 right ?

main gull
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Yes

native briar
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yay thx

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This is my last question

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<@&286206848099549185>

fleet eagle
woven radishBOT
#

WilmiRosa

native briar
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No

fleet eagle
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ok mmm

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do you know how to derivate $x^n$ ?

woven radishBOT
#

WilmiRosa

do you know how to derivate $x^n$ ?
native briar
#

wait is it

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1/x^n = x^-n

fleet eagle
native briar
#

yea sorry

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negative right

fleet eagle
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1/x^n = x^(-n)

fleet eagle
native briar
#

yeeee

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so is it

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9/x^5 = 9x^-5?

fleet eagle
#

exactly

native briar
#

fr?

fleet eagle
native briar
#

so then would 8/x be 8x?

fleet eagle
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NO

native briar
#

no?

fleet eagle
#

what about the negative? :v

native briar
#

:0

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-8x?

fleet eagle
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haha also, you write x/8 instead of 8/x jsjsj

native briar
#

_> wat

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Oh yea my bad

fleet eagle
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you got this! lets try again

native briar
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ok so

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I know that

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9/x^5 can be written as 9x^-5

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and so

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can -8/x be written as -8x?

fleet eagle
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-8x^{-1}

native briar
#

Ok

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I see

fleet eagle
native briar
#

it can be expressed as 9x^-5-8x^-1

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right? c:

fleet eagle
native briar
#

ah sorry

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I wrote it down but forgot to type it

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so then do I differentiate it

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And then switch it back to get the answer ?

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I got y’= -45x^-6+8x^-2

native briar
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LOL

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that’s the part I need assistance with 💀

fleet eagle
native briar
#

so

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if I put it all back do it get

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-45/x^6+8/x^2?

fleet eagle
native briar
#

SLEEP

fleet eagle
#

night!

native briar
#

ok thanks so much

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goodnight !

fleet eagle
native briar
#

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exotic marten
#

a

devout snowBOT
exotic marten
#

I do not understand how (x^2 -8)^2 -8 goes to the next step

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where does the -16x^2 come from?

supple knot
exotic marten
#

yes

supple knot
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(a-b)^2 = ?

exotic marten
#

i dont know that

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i know like the (x+2)(x-2) foil

supple knot
#

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

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Can you foil that right side?

exotic marten
#

hmm

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i dont understand

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ohh wait i see

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you foil it okay

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(x^2-8)(x^2-8)

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cerulean crater
#

need help with this one

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cerulean crater
#

If you reply plz tag me so I get a notification

devout snowBOT
#

@cerulean crater Has your question been resolved?

cerulean crater
#

<@&286206848099549185>

#

Image of what I tried (a bit dark, sorry 😅 )

#

no one?

#

alright, it's getting late for me

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fringe bramble
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fringe bramble
#

unsure where to start and where to go, i have aguess but it isnt feasible

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@fringe bramble Has your question been resolved?

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mint cedar
#

help

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mint cedar
#

am i doing this right

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and what is the common ratio

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<@&286206848099549185>

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im sry im a bit stupid

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i need help tho

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so pls

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tranquil lantern
#

for 1.26, would a possible disadvantage be sampling bias because its only focusing on the eastern side of US?

tranquil lantern
#

or is this question looking for me to use the answers I obtained from 1.24 and 1.25 to come with a certain disadvantage?

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neon folio
#

If i have a graph 0.5x²-1 do i graph this graph first by moving it by -1 on the y axis and then stretch it, or do i first stretch it by 0.5 and then move it on the y axis

neon folio
#

Or are both ways correct?

wooden veldt
#

Why don't you try both and see what happens

wheat pawn
#

it is not the same.
check your order of operations and what they result in

neon folio
wheat pawn
#

you start with x^2

neon folio
#

Yes

wheat pawn
#

you move it 1 down
you got x^2-1

neon folio
#

Yes

wheat pawn
#

you stretch it by .5
you got 0.5(x^2-1)

neon folio
#

Yes ok i understand

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fringe bramble
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fringe bramble
#

is this graph planar?

#

as far as i can see is no?

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@fringe bramble Has your question been resolved?

fringe bramble
#

<@&286206848099549185>

silver coral
fringe bramble
#

okay i figured

fringe bramble
silver coral
#

unfortunately no

fringe bramble
#

all goode

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tepid berry
#

is this question wrong worded?

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manic condor
#

A bit confusing i think. I'm not sure whether each was cut into 16 equal pieces or total 16 pieces as in each into 8 equal pieces.

tepid berry
manic condor
#

Ah. Lol. Badly worded then, yes.

tepid berry
tepid berry
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.close]

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bold cypress
#

Can you guys help me with this?

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bold cypress
#

I need an example of the answers

restive river
gleaming scaffold
#

I need help with a question

restive river
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gleaming scaffold
#

!help

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

restive river
#

x=0, x=-42, x=0.5, and many many more

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If you need examples, just graph it

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,w graph y=(3x+1)/x+4 and y=1

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Oh

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,w graph y=(3x+1)/(x+4) and y=1 from x=-3 to x=2

woven radishBOT
bold cypress
#

It says that 3 of these given choices are the answers

restive river
#

,w graph graph y=(3x+1)/(x+4) and y=1 from x=-6 to x=-2

woven radishBOT
restive river
#

dang

restive river
#

@bold cypress Do you have any idea where to start? Have you perhaps already tried something

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I'll be right back

bold cypress
#

Not rlly familiar with the solution

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But i’ll try sumn

restive river
bold cypress
#

Stuck here so far

restive river
#

That wasn't the method I had in mind but it's actually just as efficient so props for that

bold cypress
#

Are these correct?

restive river
#

Nothing tells you that all of these boundaries give valid solutions

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In fact with your method right now every inequality would be true everywhere, I don't know if you even noticed that

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These "boundaries" as I'm calling them just tell you where to check

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Either all of the solutions in one of the intervals are valid or they're all wrong

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@bold cypress For each of these intervals, pick a single value from it, and check it against your inequality

bold cypress
#

Im trippin balls

restive river
#

Why even bother then

bold cypress
restive river
#

...I just answered that

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The "boundaries" you found just tell you in which intervals you have to check

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The points at which (3x+1)/(x+4)=1 tell you where it crosses the line y=1 and the points at which x+4=0 tell you all of the discontinuities

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,w graph y=(3x+1)/(x+4)=1 and y=1 from x=-2 to x=2

woven radishBOT
restive river
#

??

restive river
#

Where it crosses y=1, x goes from a valid solution to a non-valid solution

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And where there is a discontinuity (where the denominator goes to 0), y jumps from -infinity to infinity

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This is why those "boundaries" give you all the intervals to consider

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Now you just need, for each interval, to pick one value from it

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And whether that value is a solution tells you whether the whole interval is a valid solution

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@bold cypress Does that make sense at all?

bold cypress
restive river
#

Yeah I was expecting that kind of response, I'll try to show it in a more intuitive way

#

whoops

bold cypress
#

It’s just that our teacher did not mention anything about graphing and boundaries. He just taught us how to find the solution set and intervals of a rational equation

restive river
restive river
restive river
#

By "true" and "valid" I just mean that it is a solution to the inequality

#

I'm going along with this whole "boundary" thing because it works quite well and because that's basically what you started doing

restive river
# restive river

@bold cypress See how your "boundaries" divide the curve into 3 sections?

#

If you slowly change x, the only way for it to go from a solution to a non-solution or vice-versa is to go through the y=1 line or have a discontinuity

#

On the right, where you replaced your < with a =, you got a point where it crosses the y=1 line

bold cypress
#

Thank you for ur time man

restive river
#

This is why as x reaches 3/2 (3x+1)/(x+4) goes from being less than 1 to being greater than or equal to 1

#

And the point at which the denominator reaches 0 gives you a discontinuity as you can see on the graph

#

@bold cypress This is why, if you picture a point following along the curve's path, as it reaches x=-4, it will go from a non-solution to a solution, and why as it reaches x=3/2 it will go from a solution to a non-solution again

#

Points where the curve crosses y=1 and points of discontinuity are where non-solutions may become solutions or vice versa

#

And because there's none of that in the interval (-4,3/2), you know that if one of the x-values within this interval is a solution then all x-values within this interval are solutions

#

Let me say that again, since in the interval (-4,3/2) the function y=(3x+1)/(x+4) doesn't cross y=1 and doesn't have a discontinuous jump, there's no way that anywhere in there it goes from a solution to a non-solution or vice versa

#

So either they're all solutions or all non-solutions

#

@bold cypress You got all of that?

#

Ping me once you get back

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orchid wasp
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pine rock
#

!show

devout snowBOT
#

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

orchid wasp
#

I have no idea what to do

neon aspen
#

as per the graph, what is f(-7)?

willow helm
#

Do you know what are constant functions?

orchid wasp
orchid wasp
neon aspen
#

f(-1)?

orchid wasp
#

5

#

What about the second function

#

It has 2 y

neon aspen
#

it's linear

#

in the form y = mx + b

#

m = slope

#

b = y intercept

orchid wasp
#

Y=-1x+3

#

?

#

@neon aspen

neon aspen
#

Check b

orchid wasp
#

3 or 6

neon aspen
#

No

#

What's f(0)

orchid wasp
#

5

neon aspen
#

Yes

orchid wasp
#

So the answer is 5 for first 2 questions?

neon aspen
#

Cuz that's the y intercept

#

The first bit is constant at 5

#

The last bit is also constant

orchid wasp
#

So what’s the answer

#

@neon aspen so my first and third answer r correct

neon aspen
#

Gtg

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elfin grotto
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elfin grotto
#

I haven't started doing this yet, I'm still pretty new to Calculus type math and are only going to the take the basic math course.

#

I was wondering if any of you have some tips, on some videos/problems to solve before tackling this problem? I don't understand how to solve this and would like to practice and understand first

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supple knot
# elfin grotto I was wondering if any of you have some tips, on some videos/problems to solve b...

This calculus video tutorial provides a basic introduction into u-substitution. It explains how to integrate using u-substitution. You need to determine which part of the function to set equal to the u variable and you to find the derivative of u to get du and solve for dx. After replacing all x variables with u variables, find the antideriva...

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elfin grotto
#

Thank you so much 🙏🙏🤩

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.solved

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restive river
#

hi i kinda dont get it where i made mistake, help. at the first picture is where i do exercise and second of the right result

violet wind
#

You shouldn't be getting any y^4 terms

#

your -6y^4 term is wrong

restive river
#

oh

#

i see

#

is that all

vagrant stump
#

Last term also 2y⁴x

restive river
#

so

#

x^2*x^2 is not x^4?

#

for example

vagrant stump
#

Its 12y⁴x

restive river
#

oh

#

i see

#

thanks

#

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tranquil sand
#

Hi everyone, I'm really struggling with an exercise in the middle of Armstrong, showing that if maps $f,g:S^{n-1}\to X$ are homotopic via $F$, then $X\cup_f S^{n-1}$ is homotopic to $X\cup_g S^{n-1}.$ \

The strategy online seems to be to see both are deformation retractions of the larger attachment space: $X\cup_F (D^n \times I)$.
(For example, a sketch here does it that way: https://math.stackexchange.com/questions/608908/ ) \

In the sketch one first constructs deformation retraction $d_f$ from $D^n \times I$ down to a space $D^n\times {0}$, along which $F$ looks just like $f$ (and similarly a deformation retraction $d_g$ to $D^n\times {1}$, where $F$ looks like $g$). \
Somehow this $d_f$ yields a deformation retraction on the attachment-spaces themselves: $(X \cup_F (D^n\times I))$ goes down to $(X\cup_f (D^n\times {0}))$. \

My question: how is this new deformation retraction on the attatchment spaces defined from $d_f$?

woven radishBOT
#

enthdegree

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@tranquil sand Has your question been resolved?

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mighty copper
#

how to do part c

devout snowBOT
mighty copper
#

this is what I did:
Dx/dt = answer of part a
solved differential equaton, got x in terms of t. then i substituted part b to solve for x

#

but i ended up getting 0

neat solstice
#

we dont want x, we want v

#

F=ma=mv'
so we get
-ae^(bv)=mv'

devout snowBOT
#

@mighty copper Has your question been resolved?

mighty copper
neat solstice
#

for c, we need x

mighty copper
#

yeaa i needed help with c

neat solstice
#

ah ok

mighty copper
#

i did dx/dt = the expression I got in a. solved the differential and substituted t from part b

neat solstice
#

do we have the same here?

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neat solstice
#

also, assuming i did it correctly
at the end of the integration to get x(t), dont sub your u back in
instead try to rewrite the u(t) with the t you got from part b)
that makes it nicer

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placid jackal
#

4x^4-4x^2+4x-1 =0

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river solar
#

are you trying to solve?

placid jackal
#

yeah for x

river solar
#

have you tried to factorise?

placid jackal
#

yes i did

#

i also tried ruffini but it doesnt have any rational roots

river solar
#

have you been given any info?

placid jackal
#

that i have to do scomposition of first member and then use product cancellation law

river solar
#

so my first thought is, what does it look similar to?

placid jackal
#

a quadratic equation?

river solar
#

yes

#

i would agree

#

except its got something extra

#

a fourth term

placid jackal
#

yess

river solar
#

now, if it didnt have that fourth term

#

if one of the terms was gone

#

could you create a quadratic - type factorisation

placid jackal
#

ahh should i try but subtracting both sides by a negative member?

river solar
#

hm, maybe not

#

so

#

lets say you only took 3 of the values

#

is it possible to create a quadratic of some sort

#

something of form

#

(a+b) * (a-b)

placid jackal
#

yes

river solar
#

or (a+b) * (a+b)

placid jackal
#

i did try that

river solar
#

what did you try?

#

im not saying thats the solution

#

but what did you try?

placid jackal
#

i basically tried every possible thing like ruffini, binomial difference and playing with different members

river solar
#

okay 1 sec

#

ill try and work you through what my approach what

#

was*

#

so, take (a+b) (a+b) or (a+b)(a-b)

#

we have a constant, and also an x^4 value

#

these can only be obtained through two of the same type, right?\

placid jackal
#

yes

river solar
#

would we use (a+b) (a+b) or (a+b)(a-b), and are we using +b on both, or -b on one

placid jackal
#

i can proceed with (2x^2)^2+ 2^)

river solar
#

uhh

#

maybe rewrite, i think you made a mistake aha

placid jackal
#

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

#

naaah

#

my bad

river solar
#

i would say, forget the rest of the equation

#

to get x^4

#

or 1

#

what will A and B be?

placid jackal
#

2x^2+1 2x^2-1

river solar
#

perfect start

#

and it will be +1, -1, since the final term is a negative

#

so if we expand that, what terms do we have?

placid jackal
#

4x^4-1?

river solar
#

great

#

so we are a little closer

#

now, what other terms could we add to the bracket

#

that doesnt create a larger power than x^4, or smaller than x^0 (or 1)

placid jackal
#

i'm thinking

river solar
#

we have (x^2, x^0)

orchid sierra
#

........Numan. 😑

placid jackal
#

yes??

orchid sierra
#

(Seinfeld reference. Carry on)

river solar
#

hhahahah

placid jackal
#

hahahaah

river solar
placid jackal
#

signs?? maybe

river solar
#

to try and create the remaining terms of the equation (x^2, and x^1)

#

maybe

#

(x^2, x^0, and we can add x^1)?

placid jackal
#

i've been working on this one for 3 hours so my brain is kind of fried rn

river solar
#

sso, just x

#

its okay ahahha

#

like

#

we could do something like

#

(2x^2 + ax + 1) * (2x^2 +bx - 1)

#

since ax * bx = c * x^2

placid jackal
#

okk

river solar
#

and ax or bx * 1 = cx?

#

do you get that?

#

now, we can either expand the general form of the brackets

placid jackal
#

nope

river solar
#

okay so

#

if you have (x+1) (x +2)

#

u can get x^2, x^1 and a constant

placid jackal
#

yes

river solar
#

the x^1 term is gotten by multiplying mixed powers right?

placid jackal
#

yess

river solar
#

when you have three powers

#

like (x^2 + 3x + 9) (x^2 + 5x - 18)

placid jackal
#

ahhh ok

river solar
#

u can get x^2 by doing x^2 and 18, or 5x and 3x

#

right?

placid jackal
#

now i get it

river solar
#

4x^4-4x^2+4x-1=0

#

thats why we can determine some guaranteed terms

#

you can only get the highest term by multiplying two things together, right?

placid jackal
#

yess

river solar
#

and the lowest by multiplying two, but the ones in between have multiple elements

#

now

#

i know that there must be a way to get 4x

#

and if we use x^2 and constants, can we get 4x?

#

are there any possible combinations?

#

at all?

#

i would suggest no, can you see why?

placid jackal
#

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

#

i think not

river solar
#

ur right

#

to get 4x

#

we must use some combination of x and constants

#

so

#

thats why

#

we have (2x^2 + ax + 1) (2x^2 +bx - 1)

placid jackal
#

ok

river solar
#

we already know we must have 2x^2 and 1 since they are used to obtain 4x^4 and -1

#

then ax and bx must somehow reach 4x and -4x^2

river solar
placid jackal
#

ax 4x^2 and bx 4x

river solar
#

what?

#

i was thinking if you multiply two x terms, you get x^2

placid jackal
#

honestly i didnt understand the qs

river solar
#

okay thats alright

#

ill try and explain

#

so we want ax*bx to hit the -4x^2 term

#

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

#

the only way to create -4x^2 is by multiplying some x terms

#

and i can guess

#

-2x and 2x

#

u actually found

placid jackal
#

yes

river solar
#

earlier u were very closer

river solar
placid jackal
#

yeah

#

how should i proceed after this?

#

ok

river solar
#

so actually

#

u can just say

#

since the only way to create -4x^2 is with 2x and -2x

#

you can just say

#

(2x^2 +2x -1) * (2x^2 -2x + 1)

#

is the solution

placid jackal
#

its like adding and subtracting nonesistent variables and breaking the existing ones

river solar
#

yes u can say that

placid jackal
#

i dont know which term is used in english to describe this method

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marble quail
#

What is the differenece between the formula for combinations and permutations?

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fair mantle
#

Can someone explain what he did from step 2 to step 3? I'm feeling very stupid right now. I understand it up to step 2, but i don't understand what he did to get from step 2 to 3

robust dust
#

just factored out (n+1)/6 from both fractions

#

the left fraction is (n+1)/6 times n(2n+1), and the right one is (n+1)/6 times 6(n+1)

fair mantle
#

OH I see i understand now. Thank you

#

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round current
#

Hi
Can anyone help me with this problem

An ellipse with its foci on the y-axis and passing through the focus of a parabola (4,0) , the ellipse pass through the Directrix of the Parabola (y²=8X) A segment with length 10 √3 Find the equation of the ellipse

The only thing i came up with was B = 4

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@round current Has your question been resolved?

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restive river
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restive river
#

This is my work. I dont know how to even start off with this question.

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#

@restive river Has your question been resolved?

restive river
#

<@&286206848099549185>

white meadow
restive river
restive river
white meadow
restive river
restive river
white meadow
#

what topic is this?

restive river
#

Trig

#

Using the compound angle formulae Rcos(x+a) and Rsin(x+a)

#

Is the name of the sheet

restive river
#

close

#

.close

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distant light
#

whats the transformation for the 3 inside the root sqaure

winter patrol
#

note that sqrt(3x) = sqrt(3) * sqrt(x)

distant light
#

okay so what would the tranformation be?

winter patrol
#

,tex .transformation rules

woven radishBOT
#

ℝam()n()v

distant light
#

ok tysm

#

.close

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idle tinsel
#

can sigma notation like this be solve with integrals?

idle tinsel
#

i was taught sigma notation is like a "rough sum" and integral is a "smooth sum" (includes non-integers) but integrals are kinda easier to work with so curious if they can solve sigma notation problems

wicked turtle
#

you can certainly express it as an integral (of a step function, for example), but if you want to compute the actual value of the sum, i don't think using an integral is going to help you

idle tinsel
#

is there a faster way to calculate sums than manually adding it?

wicked turtle
#

some types of sums, yes

#

you can use facts like $\sum_{n=1}^{N} n = \frac{N(N+1)}{2}$ for example

woven radishBOT
pine rock
#

could apply distribution and association

wicked turtle
#

in this case you're only summing four numbers, so it may well be faster just to brute force it rather than expressing it in terms of simpler sums

idle tinsel
#

if it went from 2 to 1,000,000, or some arbitary large number, how would I do a problem like that?

wicked turtle
#

something like this:
$$\sum_{j=2}^{1000000}(2j - 1) = 2\sum_{j=2}^{1000000}j - \sum_{j=2}^{1000000}1$$

woven radishBOT
idle tinsel
#

ohh

wicked turtle
#

on the right hand side, for the first sum you can use
$$\sum_{j=2}^{N} j = \sum_{j=1}^{N} j - 1$$
and use the formula I wrote above

woven radishBOT
wicked turtle
#

and the second sum is simply 999999

#

since you're adding up that many copies of 1

idle tinsel
#

i mighta messed up somewhere'

#

oh its actually a pretty number

wicked turtle
#

hmm, let's see, 2(N)(N+1)/2 - 2 - 999999 = 999999999999

#

yep checks out

#

N = 1000000 in that formula

idle tinsel
#

ah yeah I made a couple mistakes, I think I added 1,000,000 and I changed N + 1 in the formula to N + 2 because I thought maybe + 1 was the lower limit of your sum

wicked turtle
#

the -2 in my calculation is the adjustment due to starting the sum at j=2 instead of j=1

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humble flare
devout snowBOT
humble flare
#

anyone could help me with this?

graceful cosmos
#

Can you put into simpler words, what makes a set "good"?

still zephyr
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By "good" you mean well ordered set?

humble flare
#

no

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its just like

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a name of a set

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it could also be "bad"

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it doesnt matter it just has to fit the statement following

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conditions

humble flare
graceful cosmos
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@humble flare well said!

#

[1,2) isn't good, because there's nothing smaller than 1 in the set.

humble flare
#

true

graceful cosmos
#

Any change we could make to it?

humble flare
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maybe (1,0,-1,...)

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?

graceful cosmos
#

Can't be a finite set

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Note that [1,2) is a real interval

#

So 1.5 is in there

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Oh wait whoops I am the one who misread

humble flare
#

so maybe make it A= Z

graceful cosmos
#

Yes okay I see what you're saying now. Yes that works

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To just have a set of integers that trails off to negative infinity

humble flare
#

yep

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how would u write that set

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with this bracket right (

graceful cosmos
#

I was personally thinking of the real set (1,2)

humble flare
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how would that work?

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cuz there isnt any number smaller than 1

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in the set

graceful cosmos
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1 isn't in the set

humble flare
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why

graceful cosmos
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Nvm, let's just go with your suggestion.

So you should use {} and not () for a set

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So you want {1,0,-1,-2...}

humble flare
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okok thats our set

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then i would go

graceful cosmos
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Also Z is another example, that does work too

humble flare
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yeah

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i think A=Z is easiest

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so i guess

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start with WTS

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every x part of A, there exists atleast one a whcih is part of A such that a < x

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but after that idk

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would proof by induction work for this?

humble flare
graceful cosmos
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If you pick n, then n-1 is smaller

humble flare
#

what would be the base case?

graceful cosmos
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Actually that's not even induction. Just a direct proof

humble flare
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yea

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so i could prove it without induction

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is saying take a to be x-1

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then a will always be smaller than x

graceful cosmos
#

Yeah that works!

humble flare
#

okay great thanks

#

.close

devout snowBOT
#
Channel closed

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Use .reopen if this was a mistake.

#
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urban hornet
devout snowBOT
pastel pasture
#

integrate by parts

#

I suppose

devout snowBOT
#

@urban hornet Has your question been resolved?

urban hornet
#

<@&286206848099549185>

fresh cosmos
#

take secx + tanx = t

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so (secx tanx + sec^2 x) dx = dt

urban hornet
fresh cosmos
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sec ^2 x - tan^2 x= 1

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so

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1/(secx - tanx) = sec x+ tan x

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do you got it?

urban hornet
#

Yes

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Thanks

fresh cosmos
#

so sec x can be wriiten as (1/2)(t + 1/t)

urban hornet
#

.close

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#
Channel closed

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plain schooner
devout snowBOT
plain schooner
#

Was watching my professors video

#

and was wondering how she was able to figure out what type of discontinuity based on the function

#

can someone please help me understand how come the answer is removable discontinuty just based off hte function

echo vapor
#

this too easy

#

so basically

urban hornet
#

If limit at the point exists then it is removable discontinuity

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If limit dne then it is non removable

echo vapor
#

plug k into x2 and when k-1+ to the equation put it to the other side and see if the equation is still discontinous or not

plain schooner
#

ah okayyy

#

thank you guys

#

.close

devout snowBOT
#
Channel closed

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devout snowBOT
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tender grail
#

need help

devout snowBOT
tender grail
#

7 is one right?

pseudo basin
#

yes f'(7) is indeed 0

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f' is also zero at some other points tho.

tender grail
#

what makes it a 0?

pseudo basin
#

what's "it"

tender grail
#

what makes certain x points a 0

silent mesa
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you see when the line flat lines

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thats when the slope is 0

tender grail
#

wdym?

silent mesa
#

so

tender grail
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is 0 and 2 a 0 too or?

silent mesa
#

you mean f'(0) and f'(2)?

tender grail
#

yes

silent mesa
#

yea those points also have derivative of 0

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derivative is like the slope of a line at one point

tender grail
#

f'(3) and f'(5) would not be a zero correct?

silent mesa
#

f'3 and f'(5) dont have derivatives it kinda complicated but they are not 0

tender grail
#

so f'(0), f'(2), and f'(7) are zeros

#

is f'(9) a zero?

silent mesa
#

no

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think of f'(number) as the slope of that point

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at f'(9)

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the graph line is going down

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so its slope is negative and not 0

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it is only 0 when the line is not moving up or down

tender grail
#

ok so f'(8) is also not a zero

silent mesa
#

yea

#

did you learn what limit is

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like limit as x approaches 0

tender grail
#

yeah

silent mesa
#

you know how limit calculate for one point

tender grail
#

yeah i think so

silent mesa
#

well

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you can just go to one point

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and draw a line paralell to it

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and approximate the slope of that line

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its kinda what derivative is

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i will send image

tender grail
#

I feel like I already have all the zeros though

silent mesa
#

yea i think those right

tender grail
#

but it keeps marking me wrong

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Im just making sure im not missing anything

silent mesa
#

you see this is what derivative of 0 looks like

tender grail
#

yeah

silent mesa
#

you draw a flat line and its slope aligns

tender grail
#

like a tangent line

silent mesa
#

yea it is a tangent line

tender grail
#

how would you do it for f'(3) tho