#help-33

1 messages · Page 133 of 1

bold abyss
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Got the first one then :))

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Anyways my issue with it is that i would usually just figure out the equation corresponding to the graphs and then put those equal to eachother and solve for x. Issue is i cant analyse the a, b and c values in the parable (arch like one) so idk what to do

spark mason
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notice the unit squares

bold abyss
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I have in fact been staring at those

spark mason
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and where 2 functions intersect

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i think you can work the coordinates out

bold abyss
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Is that all? Theres no big calculation i gotta do?

spark mason
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i mean you can if you want but

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it's just right there isn't it

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given no information whatsoever, that's all you have and all you gotta use i guess

bold abyss
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Omg okay thank u so much!!!

spark mason
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you're welcome 👍

bold abyss
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Okay second issue

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Ive done all this

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And i dont realky get what a is? Like what does a and b determine and how do i know what a is?

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Cus if a is the percentage with wich the grap declines its way too high

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

bold abyss
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Okay this is the original problem, translation will follow shortly

twilit grove
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how did you get that number for b?

bold abyss
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Basically it says: the data below show the development in childdeaths in bangladesh i the period 2000-2019. Child deaths are measured in number of deaths for kids under the age of 5 per thousend born living.

In a model the childdeatlyness f(x) can be described by a graph
f(x)=b•a^x
Where x is years after 2000

A. Choose(?) The numbers a and b by exponential regression on all the datas (i have a seperate document with more data)

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I did the regreasion and it gave me f(x)=85,591•(o,946894)^x

twilit grove
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oh I see. it wants you to do a regression

bold abyss
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Exactly

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But then im like this dont make no sence

twilit grove
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what doesn't?

bold abyss
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I dont really get what a and b determines in the graph and if either of them is the decline of the graph then how are they positive numbers?

twilit grove
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b is the y-intercept

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i.e., the number at time 0

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it's been a long time since I did this kind of regression, but I think that the rate of decline is actually ln(a)

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,calc log(.946894)

elfin berryBOT
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Result:

-0.054568124479122
twilit grove
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so that would be a 5% decrease

bold abyss
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Ooooh okay that makes a lot more sence

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I have learned about log and ln so i get it nit thank you!!!

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*now

twilit grove
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yw

bold abyss
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But then can i just put b=(0.946894)?

twilit grove
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no, b is 85.591 or whatever

bold abyss
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Sorry i meant a

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Keep mixing them

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Imma do it

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A=(0.946894)

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I got a thrid and final question tho two sec

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This is the assignment

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It says: a quadratic polynomial f is given by
f(x)=2x^2+8x+k

A. Find the two zero points for f, when k=-4,5 (which i did)

B. Find k, so that f has exactly one zero point

(Zero point is where f(x)=0)

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I dont really know how im supposed to do assignemnt b

spark mason
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do you know the delta

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and its properties

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ax²+bx+c=0
🔺 =b²-4ac

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i'm pretty sure you've heard it

bold abyss
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I do not

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Only in relation to physics

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No actually i do know it

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Sorry we just call it d, or the discriminant

spark mason
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that's the same thing yeah

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so there's few things you gotta know

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like when d>0, there's 2 real roots to that function (meaning it intersects the x axis at 2 different points)

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and when d<0, the function doesn't intersect the x axis at all, leaving you with no real roots

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can you guess what would happen at d=0

bold abyss
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1 intersection 😎

spark mason
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👍👍

bold abyss
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How is this used i correlation with my issue tho?

spark mason
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you basically have the same function as ax²+bx+c

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it's just a=2, b=8 and c=k

spark mason
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and set that to 0 👀

bold abyss
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How can i set that to 0 tho? Like how is that possible?

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Wait it makes sence

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Sense

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Thank you so much! This has all ben such a great help!

spark mason
bold abyss
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.close

marsh citrusBOT
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lyric relic
#

!help

marsh citrusBOT
#

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

marsh citrusBOT
#

Please don't occupy multiple help channels.

lyric relic
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isnt this there are an infinte amount of solutions

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4c + 6m = 100

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8c + 12m = 200

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first equation you manipulate it

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but its gonna be

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8c + 12m = 200
8c + 12m = 200

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so what is the answer

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ok

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but that option isnt there lol

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khan academy sucks

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because you just told me the answer is

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there is an infinite amount of solution

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which is not the same thing as there is not enough information to determine the exact number of capulets and montagues

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help please

marsh citrusBOT
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@lyric relic Has your question been resolved?

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marsh citrusBOT
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lyric relic
#

!help

marsh citrusBOT
#

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

marsh citrusBOT
lyric relic
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hi

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i need help solving this systems of equation

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the two equations are

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f + p = 21
4f = p + 24

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could i divide the bottom equation by 4 to solve for f?

winter smelt
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that works, there are many ways to do it, as long as you can find an equation solely depending on one of f or p, and solve them individually, it's fine

lyric relic
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Is there an easy way to do it

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Fractions are hard

twilit grove
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substitution would be easiest here, probably

lyric relic
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Hi

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I need help

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How can I substitute

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I am not allowed to to substitute cause f is not the same as 4f

twilit grove
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you can solve for "f" right away from the first equation

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use that in the second

lyric relic
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How

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4f isn't the same as f

twilit grove
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right, it isn't

lyric relic
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So how

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I solve for f?

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But that's what I did

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Ok here is what I am trying to do

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I'm trying to isolate f so I can use whatever f is and substitute it into the first equation

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And I need help with fractions

twilit grove
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I understand. I'm saying it's easier to solve for f from the first equation, and use that in the second

lyric relic
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So the picture I sent in asking if I did it right

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Oh

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So f would be f = 21 - o

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f = 21 - p?

twilit grove
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yup

lyric relic
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Or p - 21

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Does the order matter

twilit grove
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very much so

lyric relic
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Ok so how do I know which order is correct

twilit grove
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you have f + p = 21, right?

lyric relic
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Yes

twilit grove
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and you subtract p from both sides

lyric relic
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Yes

twilit grove
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which gives you f + p - p = 21 - p

lyric relic
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Oh so it's 21 - p

twilit grove
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yup

lyric relic
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Because 21 is first

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It's the closest to the = sign

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Ahh thx

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Ok thx everyone

twilit grove
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do you understand how to use that expression for "f" in the second equation?

lyric relic
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Ho Ho Ho

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Y'all are so smart

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Yes I know how to do systems of equations

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I guess I was just being blind

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Anyways I got the answer right

twilit grove
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no worries

lyric relic
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P is 12 and f is 9

marsh citrusBOT
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@lyric relic Has your question been resolved?

marsh citrusBOT
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timid prairie
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Help pls

marsh citrusBOT
timid prairie
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<@&286206848099549185>

dawn niche
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well you know the area is $\pi {r_2}^2 - \pi {r_1}^2$

elfin berryBOT
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Potatomonke

dawn niche
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where r_2 is the outer radius

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and r1 is the inner radius

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so $\pi {r_2}^2 - \pi {r_1}^2 = 10 \pi$

elfin berryBOT
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Potatomonke

dawn niche
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when accounting for the circumferences

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$2 \pi r_2 + 2 \pi r_1 = 14\pi$

elfin berryBOT
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Potatomonke

dawn niche
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we are trying to find the width, which is r_2 - r_1

timid prairie
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is {r_2}^2 - {r_1}^2 = 10?

dawn niche
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yes

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then r_2 + r_1 = 5

dawn niche
elfin berryBOT
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Potatomonke

dawn niche
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we have the value for r_2 + r_1, which is 5, so we plug that in

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$5(r_2 - r_1) = 10$

elfin berryBOT
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Potatomonke

dawn niche
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simplifies to r_2 - r_1 = 2

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which is your answer

timid prairie
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I see

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thank you very much!

dawn niche
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np

timid prairie
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.close

marsh citrusBOT
#
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fathom mountain
marsh citrusBOT
#

Please don't occupy multiple help channels.

fathom mountain
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Did I do smth wrong? How can I proceed?

dapper bough
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(to make it easier to read)

fathom mountain
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Thx

fathom mountain
dapper bough
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i'm not sure i understand the question. could you try to explain it to me, or provide me some more context, or perhaps a picture of a prompt or something?

fathom mountain
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With z=x+iy

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<@&286206848099549185>

marsh citrusBOT
#

@fathom mountain Has your question been resolved?

marsh citrusBOT
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ruby cloak
#

In a game of chance, six cards numbered 1 to 6 are lying face down on a table. Two cards are selected without replacement and the sum of both numbers is noted. State the total number of outcomes.

lilac siren
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clearly the minimum is 3

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and the maximum is 11

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is it possible to achieve every value in the range {3,...,11}?

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@ruby cloak

ruby cloak
lilac siren
ruby cloak
lilac siren
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11 is the maximum outcome

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and all values between 3 and 11 are also possible outcomes

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thereby we know 3 to 11 are the only possible outcomes

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meaning there are 11-2 = 9 possible outcomes

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3,4,5,6,7,8,9,10,11

ruby cloak
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oh, okay

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thank you!

marsh citrusBOT
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@ruby cloak Has your question been resolved?

marsh citrusBOT
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native tapir
#

How would i do q13

marsh citrusBOT
native tapir
lilac siren
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like we did before

native tapir
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Did i do this wrong

lilac siren
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careful careful

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it's the dot product

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not multiplication

native tapir
lilac siren
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and after that just remember that a*a = |a|²

native tapir
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Oops...

lilac siren
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b*b = |b|²

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and "a is parallel to b"

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so let's remember what the dot product means

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we project a onto b and then multiply the lengths

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but if a is parallel to b

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then a projected is just a again

native tapir
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Is magnitude squared just the original value

lilac siren
native tapir
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So magnitude 6 squared is just 6?

lilac siren
native tapir
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Ohhh u rite

lilac siren
native tapir
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OOPS.

lilac siren
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:D

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nw

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therefore since a and b are parallel: a * b = |a| * |b|

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because a_projected = a

lilac siren
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left is vector dot product

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right is normal multiplication

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so written in latex:

native tapir
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is it magnitude ab?

lilac siren
native tapir
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Ohhh

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I SEE

lilac siren
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as they're parallel

marsh citrusBOT
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@native tapir Has your question been resolved?

marsh citrusBOT
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pseudo aspen
#

I'm kind of lost of what to do at this point, using partial fractions

fervent rampart
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set that equal to the original function

pseudo aspen
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okay

rocky lark
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$x^2(.....)+x*(.....)+....$ you could try doing something like this

elfin berryBOT
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BobTheBuilder

still temple
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you can find the value of A and c by substituting x equals 0 and -1

pseudo aspen
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how did you know that's what i was supposed to do?

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i'm confused there

mighty gyro
still temple
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🤨

rocky lark
pseudo aspen
rocky lark
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What did you not understand?

pseudo aspen
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literally everything, i don't know that x^2(...)+x*(...) is

pseudo aspen
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i basically don't know how i handle 5-x

pseudo aspen
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all the examples we did had a x^2 if there was a x^2 in the Ax^2 place

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oh so Ax^2+Bx^2, since there's no x^2 in the 5-x numerator is 0?

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we didn't do any examples like that so i'm flabbergasted

pastel granite
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yes the coefficient on the x^2 term must be 0

pseudo aspen
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that gives me A=5, B=-5, C=-6

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then i just do 3 integrals with those values

pastel granite
pseudo aspen
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that gives me that, right?

pastel granite
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be careful with the last integral

pseudo aspen
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ah u sub

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it's saying this is wrong???

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without and without the bars

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god i hate this software so much

late geode
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don't need () when you have | |

pseudo aspen
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it's the software being a dumbass, i needed to use their specific bars

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I couldn't type in my own

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the class made us pay $130 for this software and it doesn't even work

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love it so much

pastel granite
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that is upsetting it seems to be correct

marsh citrusBOT
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@pseudo aspen Has your question been resolved?

pseudo aspen
#

have i done something wrong here?

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i can't figure out a way to find B or C

pastel granite
pseudo aspen
pastel granite
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yes

pseudo aspen
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giving me C = 2

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then i just use -1 + B + 2 = 0

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and B = -1

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got it, that makes sense

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simple algebra that i forgot lol

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this whole process seems like it's more algebra based than calculus ngl

rocky lark
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if you did the previous calculations correctly everything is correct for now

pseudo aspen
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yeah, got it right!

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for this problem, i would need to use the division stuff?

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in my notes i have something like this

rocky lark
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but if you do the calculations you see that the numerator has a lower degree than the denominator, so no

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You do the division only if the numerator has a degree greater than or equal to that of the denominator

pseudo aspen
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ahh, i see

marsh citrusBOT
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@pseudo aspen Has your question been resolved?

pseudo aspen
#

just going to keep this open for a little bit longer

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if i see no help channels available, i'll close it though

pseudo aspen
#

.solved

marsh citrusBOT
#
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marsh citrusBOT
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lethal bridge
#

I don’t really understand what’s going on here

lethal bridge
#

i can still ask it here

spark mason
#

great for you

lethal bridge
#

???

spark mason
#

We are a mathematics server but we are a part of a larger network of science-centered servers. If you are interested in other scientific topics, check out the servers listed in #old-network.

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this quite literally the first thing written in #info

lethal bridge
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why are you minimodding for no reason

spark mason
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whatever i give up

lethal bridge
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dont know why youre making such a big fuss if youve been in the server long enough youd see that this isnt unusual

crystal wraith
lethal bridge
#

right

crystal wraith
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The fastest of those electrons had kinetic energy that you find out using the equation hυ = Φ + KE

fathom ridge
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hu

crystal wraith
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It's not u?

lethal bridge
#

hf

crystal wraith
#

υ

lethal bridge
#

hu?

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whats u

crystal wraith
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$\nu$

elfin berryBOT
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! What the hell am I doing here?

lethal bridge
#

nu?

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u?

crystal wraith
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frequency

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f

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God damn it.

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sure, f

lethal bridge
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in my book frequency is denoted as f

crystal wraith
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Fair enough.

lethal bridge
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so what hapens after the photoelectrons are emitted?

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it turns into photocurrent?

crystal wraith
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Yes, it normally would have.

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But those electrons are now stopped because of the potential applied.

lethal bridge
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this is the voltage source im guessing?

crystal wraith
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Yes.

crystal wraith
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That's the idea.

lethal bridge
crystal wraith
lethal bridge
#

so if the voltage is stopping the photoelectrons from running through the wire, how does it reach the collector?

crystal wraith
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And the voltage applied only acts after the electrons reach the collector.

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They'd have had kinetic energy still but this voltage now acts against the electrons' motion.

lethal bridge
#

is this the direction in which this is happening?

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so it goes to the collector first?

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this is more like it didnt mean to add the extra red line

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or is it the other way around

proper zodiac
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Other way, conventional current (+ to-) opposes electron flow. Increasing voltage makes more electrons "build up at the collector" meaning the photoelectrons don't want to be there more

lethal bridge
#

O

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so if in the question it says "all emitted photoelectrons are gathered by a collector" if the voltage is stopping the photoelectrons from flowing in the wire, how does the collector ever gather it?

proper zodiac
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At the start of the experiment the voltage is low enough that all photoelectrons that want to get to the collector, do so

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As you increase the voltage less and less reach the collector until none do

lethal bridge
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ohhh

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Im confused why increasing voltage would reduce the current detected? I thought it would do the opposite no? from V=IR voltage is directly proportional to current

cursive raptor
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Yo you need help here still? I think I get it

lethal bridge
cursive raptor
#

Mk what do you want me to explain?

cursive raptor
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The voltage is essentially travelling in the other way to the photoelectron current

lethal bridge
#

oh

cursive raptor
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This lowers the current of the photoelectrons emitted; as the collector becomes more "negative" the photoelectrons don't want to travel there as much, they're being resisted (repelled)

lethal bridge
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ahh okay

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so this reduces the kinetic energy of photoelectrons and makes it move through the wire more slowly?

cursive raptor
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Yeah, so the voltage is known as the stopping voltage, and is the voltage that resists the photoelectrons

lethal bridge
#

ohhhhhh alright that makes sense

cursive raptor
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Only the electrons that have enough KE can bypass this to reach the collector

lethal bridge
cursive raptor
#

I'll admit I have no idea if the stopping voltage is a current, I dont think it is

lethal bridge
#

wait so the negative side of the voltage source is connected to the collector or something, is that why the voltage is fighting against the photo current?

cursive raptor
#

Dude get lost

cursive raptor
#

The stopping voltage makes the collector more negative which increases the amount of KE required for a photoelectron to make it to the collector

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I don't know how the voltage is applied...

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Let me cook

lethal bridge
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alr lmao

cursive raptor
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I'm confused because if that symbol is a battery then wouldn't the stopping voltage induce a current on the ammeter?

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I'm learning this topic rn btw

lethal bridge
cursive raptor
#

Wait hang on its not closed, theres no current

cursive raptor
lethal bridge
#

the metal here acts as a current source

cursive raptor
#

Nvm, I was thinking about the battery, I get it

cursive raptor
lethal bridge
#

wait so im kind of confused, does the voltage source create electrons? or is it just a electrical force that guides the electrons

cursive raptor
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It's impossible to create electrons, it essentially gathers them

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And having more electrons at a point makes that point more negative, which would be the collector in this case

lethal bridge
#

so it just provides the force for electrons to flow in the circuit

#

?

#

ohh ok

#

i think i get it now

#

so if this was negative to positive, there would be no force the photocurrent has to fight against?

cursive raptor
#

Yea, it would be attracted

#

Because the collector would be positive

lethal bridge
#

kk

#

i get it now

#

thanks

cursive raptor
#

Hope that helps

marsh citrusBOT
#

@lethal bridge Has your question been resolved?

marsh citrusBOT
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open kayak
marsh citrusBOT
#

Please don't occupy multiple help channels.

open kayak
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Oops, closed the other one

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#

@open kayak Has your question been resolved?

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marsh citrusBOT
vernal forge
#

not sure what answer do you want to get, it's like asking what's the difference between an orange and an apple

#

they are two distinct rules

#

sine rule
a/sin(A) = b/sin(B) = c/sin(C)

cosine rule
c^2 = a^2 + b^2 - 2*a*b*cos(C)

marsh citrusBOT
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plain crescent
#

if $y=x^2-3x$, then $\frac{dy}{dt}=\frac{dx}{dt}$ at x = ?

elfin berryBOT
#

Joeller

plain crescent
#

$\frac{dy}{dt}=2x\frac{dx}{dt} - 3\frac{dx}{dt}$ = $\frac{dx}{dt}(2x-3)$

elfin berryBOT
#

Joeller

plain crescent
#

and from this

#

$\frac{dy}{dt}=\frac{dx}{dt}(2x-3)$, then $\frac{dx}{dt}=\frac{(\frac{dy}{dt})}{2x-3}$ = $\frac{dy}{dt}\frac{1}{(2x-3)}$

elfin berryBOT
#

Joeller

plain crescent
#

and since dy/dt=dx/dt so we'll just remove them so we'll end up with

#

$2x-3=\frac{1}{2x-3}$

elfin berryBOT
#

Joeller

plain crescent
#

$4x^2-12x+9-1=0$ divide by 4, $x^2-3x+2$

elfin berryBOT
#

Joeller

plain crescent
#

$x=1,x=2$

elfin berryBOT
#

Joeller

plain crescent
#

and I got both of them in the choices

#
  • the answer was 2
plain crescent
still temple
plain crescent
#

its crazy that they have them both in the choices

#

I'll have to ask my teacher about this

#

.close

marsh citrusBOT
#
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distant lichen
#

what role does n=2 play in this

marsh citrusBOT
distant lichen
#

if im finding convergence or divergence

marsh peak
distant lichen
#

oh ok

#

thanks

latent coral
#

it shouldn't really make a difference, n = 1 produces a finite term so if this sum diverges then the sum would diverge even if n started at 1, and likewise if this converges then adding the n = 1 term will still lead to a finite sum

distant lichen
#

this sum coverges tho

tired oxide
distant lichen
#

ohhhhh ok

tired oxide
#

if the whole sum converges then starting one term earlier doesn’t make a difference 👍

distant lichen
#

alright thanks

#

.close

marsh citrusBOT
#
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twin ether
#

How do I solve b)

marsh citrusBOT
still temple
#

no clue i'm restarted

twin ether
#

a) is 7

dawn niche
elfin berryBOT
#

Potatomonke

twin ether
#

$\frac{f(x-0.01)-f(x)}{0.01} = 7$

elfin berryBOT
#

rynite

twin ether
#

I think this is what I should be solving

#

but idk if its possible

merry pewter
#

have you learned power rule yet?

twin ether
#

nope

pseudo flax
twin ether
#

so what do I do now

boreal rose
dawn niche
twin ether
#

in the book, one possible answer given is (4.5, 3)

#

idk how they got that tgho

#

tho*

dawn niche
#

its right between 4 and 5

#

its the midpoint of that line

twin ether
pseudo flax
pseudo flax
# twin ether yes

if you were to find a point **common ** to the instantaneous rate and the average rate , what could you do?

#

think in terms of x values

twin ether
#

not one

pseudo flax
#

think about the equations for each

versed pagoda
#

Is this a cubic?

#

I think you'll likely need to solve the cubic and then check where df(x)/dx = 7

pseudo flax
versed pagoda
#

because intermediate value theorem isn't enough here

versed pagoda
pseudo flax
#

@twin ether try to set the equations for instantaneous and average equal to each other

#

like this

versed pagoda
#

is f specified though?

pseudo flax
#

average has already been found

versed pagoda
#

I understand

#

but f isnt given...

limber hearth
versed pagoda
#

well not necessarily....you're assuming its a cubic but it could be a crazier function

#

anyway considering its a cubic we can do it quickly enough

twin ether
elfin berryBOT
#

rynite

twin ether
#

like that?

fervent yarrow
versed pagoda
#

so anyway cubic is (x^2 -4)(x-2) = x^3 - 2x^2 -4x + 8

#

derivative is 3x^2 - 4x -4 which we want to be 7

#

3x^2 - 4x-11=0

#

just solve it

#

🤷‍♂️

twin ether
#

im confused asf

versed pagoda
#

ok

#

have you learned derivatives?

twin ether
#

no

versed pagoda
#

hmmm

#

but you've seen limits?

twin ether
#

no

versed pagoda
#

so what has been taught in calculus?

twin ether
#

im not taking calculus

versed pagoda
#

which grade are u in

twin ether
#

11

#

its a part of my advanced functions

#

course

pseudo flax
twin ether
#

a single chapter

twin ether
pseudo flax
#

limits are taught first

versed pagoda
#

ok you shouldve seen limits

#

but like ney said

twin ether
#

hm I didn't

versed pagoda
#

she gave you the def of limits

#

anyway ok

#

so let's do it slowly

#

assume the function is a cubic

#

what are it's roots

#

they're specificed?

#

from the graph

twin ether
#

yeah uh

#

-4 ,2, 4

versed pagoda
#

ok

#

so the function can be inferred right?

twin ether
#

i found it

versed pagoda
#

(x-4) x (x+4) x (x-2) right

twin ether
#

yea

#

and a is around 0.26

versed pagoda
#

ok its this x^3 - 2x^2 -4x + 8

#

right?

twin ether
#

yep

versed pagoda
#

ok

#

so you're looking to find an x such that

#

[f(x+h) - f(x)]/h

#

with h being super tiny (we'll quantify)

versed pagoda
twin ether
#

yeah I understand that

versed pagoda
#

ok

#

so keeping x and h as variables

#

compute f(x+h) - f(x)

fervent yarrow
versed pagoda
twin ether
twin ether
versed pagoda
#

f(x) is x^3 - 2x^2 -4x + 8

#

f(x+h) is (x+h)^3 - 2(x+h)^2 -4(x+h) + 8

twin ether
#

oh

versed pagoda
#

open up the (x+h) powers

#

and then subtract it with f(x)

twin ether
#

alright

#

sec

twin ether
versed pagoda
#

no that's not right

#

the constant should disappear

twin ether
#

what constant?

versed pagoda
#

16

#

8 and 8 cancel

#

you're subtracting not adding

twin ether
#

ok k

#

x^(3)-2x^(2)-4x+8 -(x+h)^(3)-2(x+h)^(2)-4(x+h)+8

is that what I should be solving

versed pagoda
#

the other way

#

f(x+h) - f(x)

twin ether
#

ah right

twin ether
#

oops

#

too many variables

#

the 8s still dont cancel out

twilit grove
#

you have to distribute. it's minus all of f(x)

twin ether
#

ah

#

i forgot about that 😅

#

3x2h+3xh2+h3−4hx−2h2−4h

is that right

#

now

#

$3x^2h + 3xh^2 + h^3 - 4hx - 2h^2 - 4h$

#

clearer

versed pagoda
#

no its not

elfin berryBOT
#

rynite

versed pagoda
#

3x^2 shouldnt exist

#

ok

twin ether
#

yeah mb

#

so what now

#

do i equal that to 7

#

and solve

versed pagoda
#

sounds reasonable

#

now divide this by h

twin ether
#

alr

#

ill do 0.01

#

wait you mean h

#

like the value itself

#

or literally "h"

versed pagoda
#

no the variable h

twin ether
#

ok

twin ether
elfin berryBOT
#

rynite

twin ether
#

right?

versed pagoda
#

yeah

#

so now take h to 0

#

you should be left with 3x^2 - 4x - 4

twin ether
versed pagoda
#

thats what it means to have instantaneous change

#

you'll learn that in limits

twin ether
#

oh ok

twin ether
versed pagoda
#

yea

twin ether
#

and 2.69

#

is that right

twilit grove
#

yeah looks very close

versed pagoda
#

I mean did we make a mistake

#

because while the roots look fine

#

-1.36 and 2.69 on the graph are decreasing points

#

I think we got the function wrong

twin ether
twilit grove
#

yes, the function was wrong

versed pagoda
#

its (x-4) * (x+4) * (x-2)

twilit grove
#

the zeros are -4, 2, 4

versed pagoda
#

so (x^2 - 16) * (x-2)

twin ether
#

oh

versed pagoda
#

mb sorry

#

x^3 -2x^2-16x+32

twin ether
#

ight sec

versed pagoda
#

do the same thing as before

#

good practice 🙂

#

you should get 3x^2 - 4x - 16 = 7

#

to be solved

twin ether
#

also -1.5986

versed pagoda
#

no that's not it

#

roots are 3.51, -2.18

#

did u figure it out?

marsh citrusBOT
#

@twin ether Has your question been resolved?

twin ether
#

i got ur answer now

versed pagoda
#

ok cool

#

good luck

twin ether
# versed pagoda ok cool

I have a question though, I don't understand why we didn't consider a in the equation, vertical shift/comp

versed pagoda
#

whats a?

twin ether
versed pagoda
#

im confused where are u getting -0.26 from?

limber hearth
#

can't be negativ

versed pagoda
#

no it can be

#

-2.18 is a valid solution

limber hearth
#

i think it's approximately 0.26 what he wanted to say

#

with the ~ symbol

versed pagoda
#

ah ok

#

thought it was a - lol

marsh citrusBOT
#
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spiral merlin
#

How do I express this equation?

marsh citrusBOT
dawn spear
#

take 3^p+2 common

#

from the 3 terms

spiral merlin
#

Hmm how

dawn spear
#

acc to you, what should be left after you take 3^p+2 common from the first term?

spiral merlin
#

Factorise 3?

dawn spear
#

wdym factorise 3

spiral merlin
#

Like take out 3 from the 3 terms?

dawn spear
#

first just take out 3^p+2 from the first term

#

and tell me what do you get

spiral merlin
#

1^1

dawn spear
#

no

spiral merlin
#

Hmm I don’t get it 😭

marsh citrusBOT
#

@spiral merlin Has your question been resolved?

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ripe python
#

Is this correct

marsh citrusBOT
ripe python
#

But in book says its x= 1/12

#

I mean key

#

Are you sure

#

Okay

#

Thank you

#

.close

marsh citrusBOT
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tacit narwhal
marsh citrusBOT
tacit narwhal
#

can someone help me solve this

night turtle
#

Try consider the general expression for each individual term

tacit narwhal
#

general expression ???

night turtle
#

Well you know the binomial theorem right?

tacit narwhal
#

yep

night turtle
#

$(x+y)^n = \sum^n_{k=0} {n \choose k} x^{n-k} y^{k}$

elfin berryBOT
night turtle
#

The general expression is ${8 \choose k} (\frac{x^3}{2})^{8-k} (\frac{a}{x})^{k}$

elfin berryBOT
night turtle
#

Since we are looking for the constant term, we want all the x to cancel out

#

And so we want to find k that satisfies

versed pagoda
#

look at terms of the form $C^8_k x^{3k}/2^k a^{8(8-k)}/x^{8-k} = C^8_k x^{4k-8} a^{8(8-k)}/2^k$

#

n is 8

elfin berryBOT
versed pagoda
#

so k=2 is the valid term for the constant

tacit narwhal
#

this is the way my teacher did it but i want to know why x=1

versed pagoda
#

so 8C2 x a^{8 x 6}/2^2 = 7 a^48 = 5103

#

so a^48 = 729

#

729 = 3^6

#

so a^48 = 3^6 => a^8 = 3

night turtle
versed pagoda
#

a = 3^{1/8}

night turtle
#

Since we are looking for the constant term here
There wouldn't be any x

tacit narwhal
#

why is it 1

night turtle
#

Is 5x a constant?

tacit narwhal
#

no i dont think si

#

now im getting confused

#

???

night turtle
#

If the term has x in it, then it is not a constant right?

tacit narwhal
#

tthe question is asking for the a and r vlue

night turtle
#

e.g. 510, -0.888, e are all constants
5x, 99/x^5, x^2 are not constants

#

Looking back to your question
We know that the constant term is 5103 (which has no x)

#

Meaning that the expression for the constant term $\frac{x^{24-3r}}{x^r}$ must be a constant, i.e. 1

elfin berryBOT
tacit narwhal
#

ok

#

thnanks

#

bye

#

.close

marsh citrusBOT
#
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drifting oar
#

How do I find the highest common factor of s to the power of 8 and s to the power of 6

tired oxide
#

it's easy in this case since s^6 divides s^8

still temple
#

its s to the power 6

tired oxide
#

it's just like trying to find the HCF of 2 and 8, well it's 2 because 2 divides 8

drifting oar
#

Would it be okay for you to break that down for me?

#

So I can understand how it divides etc?

tired oxide
#

yeah i can, if you're trying to find the HCF of 2 and 8, we know that 2 is a factor of 8 and also of 2, but also there are no bigger ones since 2=2, so nothing higher will be a factor of 2

#

similarly, S^6 is a factor of both S^6 and S^8, but if you try anything higher, it will no longer be a factor of S^6

tired oxide
#

because S^6 * S^2 = S^(6+2) = S^8

#

using our exponent rules

drifting oar
#

Got it

#

So the highest common factor would be s^6?

tired oxide
#

yep

drifting oar
# tired oxide yep

Thanks! and how would I find the highest common factor of h^8 z^5 and h^7 z^6?

tired oxide
#

you would take the lower of the two powers in each and combine them. think "the max capacity for h's in h^8z^5 is 8" and for h^7z^6 it's 7, so we try to fill both with h's we can only fit 7 until one of them can't fit any more

#

and do the same for the z's

#

so how many z's go into each term?

drifting oar
#

Im sorry, I dont completely understand

tired oxide
#

that is okay, we should start at the basics actually, you are familiar with the term HCF? if not, we should start there.

drifting oar
#

yep

tired oxide
#

okay great

drifting oar
#

🙂

#

I havent done highest common factors of variables and exponents until today so def a learning curve 😂

#

Pretty sure ive got it nailed for variables now though 🙂

tired oxide
#

i know this sounds simpler than what you want, but it's really instructive

drifting oar
#

Finding common multiples eg: 1,18 and 1,24 then working my way up till I find the highest one that goes into both

#

So in this one it would be 6

#

6x3 and 6x4

tired oxide
#

yes. okay, also do you know about prime factorizations (i promise i am getting somewhere with this)

drifting oar
#

Working on it, not completely there yet

tired oxide
#

okay, the point is that 24= (3)(2)^3 and 18 = (2)(3)^2

#

and we computed the hcf to be 6 = 2*3

#

so what i would do to find the hcf was to look at the minimum exponent of each of the primes (which in your case will be the variables) that divide it.

#

so we can go back to h^8z^5 and h^7z^6

#

i look and see "what is the minimum exponent of the h's" and i see that it's 7, and "what is the minimum exponent of the z's" and I see that it's 5

#

so we can just say that the hcf is h^7z^5

#

and in fact you can check for yourself that that's indeed the highest common factor

drifting oar
#

So the highest common factor is the minimum exponent of both variables in the equation?

tired oxide
#

also be careful about using the word equation

#

there is no equation here!

drifting oar
#

So the highest common factor is h^7 and z^5?

tired oxide
#

it's the product of those

#

h^7z^5 is one expression

drifting oar
#

So what would I need to do to find the hcf?

tired oxide
drifting oar
#

Got it! So if I were to find the hcf of 35a^2 x^4 and 25a^3 x^6 I would do the same thing?

tired oxide
#

yes, this one is slightly different because you now have numbers out front, right? but do the variable part first, and then the number part after

drifting oar
#

Got it, so i would find the hcf of 35 and 25 which is 5?

tired oxide
#

yep

#

and then now do the variable part

drifting oar
#

and then find the minimum exponent for each variable?

tired oxide
#

yep

drifting oar
#

so a^2 and x^4

tired oxide
#

yrp

#

so now we combine them together

drifting oar
#

So would it be 5a^2x^4?

tired oxide
#

yeah

drifting oar
#

Thank you so much!

drifting oar
#

I have a few more which are a bit tricky

tired oxide
#

sure yeah go for it

#

I won't say much though, you pretty much have the technique down now

drifting oar
#

L(5-2x) and 3(5-2x)

tired oxide
#

okay so treat 5 - 2x as a variable

#

so we can do the numbers out front first, we have 3 on the right and just a 1 on the left (remember that if there is no number in front that just means there is an invisible 1)

drifting oar
#

So you mean 1L and 3?

tired oxide
#

and then go variable by variable. if there is ever not a variable in the either expression, then just leave it out, for example you won't have any L's in your HCF

drifting oar
#

Just making sure Im looking at the same part :laugh:

tired oxide
#

L is just another variable

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i am assuming

drifting oar
#

So where did the 1 come from?

#

Looking at the L right?

tired oxide
#

the 1 is literally always there. L(5-2x) = 1* L(5-2x)

drifting oar
#

Got it

#

just making sure we are looking at the l

#

1x5 and 1x-2x for the left bracket?

#

or do we not expand and just find the hcf?

tired oxide
#

don't expand

#

you can directly find the hcf, just treat (5-2x) like a variable and do what we did before

#

actually every time you try to find the hcf you'll try to get them in a product of terms like this

#

so this is like the best case we could hope for

drifting oar
#

Sorry, ive got a bit of brain fog atm. would 5-2x be the minimum variable sincw its the same in both brackets?

#

since

tired oxide
#

if you're saying what I think you're saying then yes..

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5-2x is the variable, min exponent is 1

drifting oar
#

So how would I find the hcf?

tired oxide
#

just like before. take hcf of the numbers, which is HCF(1,3) = 1, then the min exponent of the L's, which is 0, and then the min exponent of the 5-2x's, which is 1

#

so overall we just get (5-2x)^1

drifting oar
#

So the hcf is (5-2x)^1?

tired oxide
#

yeah

#

notice that (5-2x)^1 = 5-2x

#

so we can just say 5-2x

drifting oar
#

So the simplified varsion is 5-2x?

tired oxide
#

yea

drifting oar
#

Thanks! are you any good at factorising by chance?

tired oxide
#

yes, but i have to go to sleep, it is 4 am and i have to be up in the morning

drifting oar
#

ahh, sorry to be using your time like this!

tired oxide
#

other people here are also good at factoring though

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no it's okay, i like doing this

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i like doing math help in my free time it's fun.

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I just get carried away sometimes and stay up too late :P

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good luck factorizing though.

drifting oar
#

Thank you so much, Ive been very sick for the past term and havent been able to come to lessons! (+ we got a new teacher)

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This has significantly helped me 🙂

tired oxide
#

lol yeah that can be really discouraging. hopefully you are not too far behind, i know that it can be rough in that situation

drifting oar
#

Not too far behind not that youve helped me!

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Thanks so much again!

#

How do I factorise 14l^5 +8l^4 g^4

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<@&286206848099549185>

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Could you help break that down for me?

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im sorry, i dont seem to be catching on. Could we try k(-6+y^2) +5a (-6+y^2)

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is v^2-13v

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trinomial

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<@&286206848099549185>

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Why is it trinomial?

#

would 2d^2+34 be the same then?

#

So thats also both quadratic and trinomial?

#

same with -6x+36?

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but not with y^2?

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<@&286206848099549185>

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is y^2 quadratic and trinomial?

#

so all of those are quadratic and trinomial?

marsh citrusBOT
#

@drifting oar Has your question been resolved?

#
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#
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drifting oar
#

Is the factorised version of 25n^2-25 = 25 (n-1)(n+1)

late geode
#

yes

drifting oar
#

is the factorised version of 25q^2-f^2 = (5q+f)(5q-f)

late geode
#

yes

drifting oar
#

is the factorised version of 25t^2-25h^2 = (t+h)(t-h)

#

Is the factorised version of 4c^2n^2-49v^2 = (2cn+7v)(2cn-7v)

marsh citrusBOT
#

@drifting oar Has your question been resolved?

drifting oar
#

is the factorised form of 14l^5+8l^4g^4 = 2l^4(7l+4g^4)

#

<@&286206848099549185>

buoyant jetty
#

,iamnot helper

elfin berryBOT
#

Removed the Helpers role from you.

buoyant jetty
#

,w factorize 25t^2-25h^2

buoyant jetty
#

,, (t-h)(t+h) \cdot 25

elfin berryBOT
#

938c2cc0dcc05f2b68c4287040cfcf71

buoyant jetty
#

,w factorize 25q^2-f^2

buoyant jetty
#

I think you get the idea

buoyant jetty
drifting oar
#

kk

#

would the factorised version of 14l^5+8l^4g^4 = 2l^4(7l+4g^4)

buoyant jetty
#

,w factorize 14a^5+8a^4b^4

drifting oar
#

.close

marsh citrusBOT
#
Channel closed

Closed by @drifting oar

Use .reopen if this was a mistake.

marsh citrusBOT
#
Available help channel!

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

celest harbor
#

how would i intergrate y? so far im at $3 \int \frac{1}{u}dx => \frac{(4x+1)^{\frac{1}{2}}}du = dx => 3 \int \frac{(4x+1)^{\frac{1}{2}}}{2u} du$ but i feel like theres an easier way of doing this

elfin berryBOT
#

morphine_addiction

celest harbor
#

hold on this latex is buggin

naive fox
#

ok... I think you forgot the square root or did you let your $u = \sqrt{4x+1}$?

elfin berryBOT
naive fox
#

ok... suppose you let your $u = \sqrt{4x+1}$. What is your $du$?

elfin berryBOT
naive fox
#

actually, you have it already

celest harbor
#

ye 2(4x+1)^(-0.5)

naive fox
#

one trick to make this simpler is to see that $u^2 = \sqrt{4x+1}$ then, $dx = \frac{u}{2} du$ but let's stick with what you have for now

elfin berryBOT
naive fox
#

well, you will have a similar result anyways but with different bound

naive fox
#

yes. it is the same with what you did

#

just write it in different way.

#

Anyways, I think you forgot square root on 3 and your solution should be fine

celest harbor
naive fox
#

well, you know that $u = \sqrt{4x+1}$

elfin berryBOT
naive fox
#

then your $du = \frac{2}{(4x+1)^{\frac{1}{2}}} dx = \frac{2}{u} dx$

elfin berryBOT
naive fox
#

do you agree?

celest harbor
#

yes

naive fox
#

Then, your integral will simplify to ...

celest harbor
#

1/2

naive fox
#

exactly

celest harbor
#

so 3x/2?

naive fox
#

well, close

#

not quite

celest harbor
#

i mean u

naive fox
#

still... really close

celest harbor
naive fox
#

well, no. But yes, you should have $\sqrt{3}$

elfin berryBOT
naive fox
#

it is $\left.\frac{\sqrt{3}u}{2}\right|_{a}^{b}$

elfin berryBOT
celest harbor
#

hold on im buggin, 1/2(sqrt(3)*u

naive fox
#

yes.

#

Now, you need to find the boundary with respect to $u$ (or just substitute $x$ back) and you should be done

elfin berryBOT
naive fox
#

yes, if you use $u$ that is

elfin berryBOT
celest harbor
elfin berryBOT
#

morphine_addiction
Compile Error! Click the errors reaction for more information.
(You may edit your message to recompile.)

naive fox
#

yes.

celest harbor
naive fox
#

left side, you are basically putting the $x = 0$ and $x = 20$ down already and the right side is you have not done anything yet.

elfin berryBOT
naive fox
#

actually...

#

since $u=(4x+1)^{\frac{1}{2}}$, $x = 0 \rightarrow u = 1$

elfin berryBOT
naive fox
#

and $x = 20 \rightarrow u = \sqrt{81} = 9$

elfin berryBOT
naive fox
#

you should get the same result

celest harbor
naive fox
#

well, you can't get different result when left side (u) is the second step of the right side (x)

#

so, for $u$, $\frac{9\sqrt{3}}{2} - \frac{\sqrt{3}}{2} = \frac{8\sqrt{3}}{2} $

elfin berryBOT
naive fox
#

for $x$, $\frac{\sqrt{3}}{2}(4(0) + 1)^{\frac{1}{2}} = \frac{\sqrt{3}}{2}$

elfin berryBOT
naive fox
#

and $\frac{\sqrt{3}}{2} (4(20)+1)^{\frac{1}{2}} = \frac{9\sqrt{3}}{2}$

elfin berryBOT