#help-36

1 messages · Page 178 of 1

tired walrus
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maybe we could read it together to find out how much of an issue it is.

strong flax
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hmm

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ok

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i dont have it in hand

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i guess i could get it

tired walrus
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yes, go get it.

strong flax
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well

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i know its either 32k or 36k

proper dagger
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per how long?

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a month? a year?

strong flax
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why dont we just look for both cases

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3 years

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36 months 32k

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or 36 months 36k

tired walrus
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ok so 32,000 miles per 3 years.

strong flax
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yea

proper dagger
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so ~10,667mi/yr

strong flax
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this will just be alot easier ngl

tired walrus
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in the meantime, im seeing 8 breaks per week in your current schedule.

strong flax
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if i just lived on campus

tired walrus
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so assuming you drive to and from home on each one of them (generous)

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that'll be 9 * 2 * 8 = 144 extra miles per week

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with an academic year 39 weeks long (give or take) that comes out to

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,calc 144 * 39

soft zealotBOT
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Result:

5616
tired walrus
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about 5,500 miles driven extra

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per annum

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ok so i guess if you drove back and forth every single break this would eat like half of your distance limit.

strong flax
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i see

tired walrus
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if you stay behind for the shorter breaks between your bio and chem classes, which are only 1.5 hours long and so conceivably could be spent on campus without rotting too much, all this driving will only eat 25% of your limit.

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do you have anywhere else to drive regularly besides uni?

strong flax
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i guess work

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where i work its kind of close actually

proper dagger
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how far?

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and i'm guessing you work only on weekends?

strong flax
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7 minute drive

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2 miles

tired walrus
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how many days a week?

strong flax
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i actually work for my mom and dad

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so i can just chill out there

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in the business and theyll let me chill out and relax

tired walrus
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ok great

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wait actually

strong flax
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maybe

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i think i just need to bite the bullet

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i mean autumn quarter is only like 11 weeks

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then my suffering ends

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its either that or i can just drop every single class and create a different schedule

tired walrus
strong flax
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home to uni is 9 miles 15 minutes

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uni to work is 7 minutes 2 miles

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so that must mean home to work is 7 miles

tired walrus
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that so?

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do you drive past your workplace on your way to uni?

strong flax
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yes

tired walrus
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right ok

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so you can drive to work during your multi-hour breaks and chill out there instead of going all the way home

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that way your extra gas costs from that become even lower

strong flax
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yea

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yea

tired walrus
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so it is even less of an issue

strong flax
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ok i see

tired walrus
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so like it's up to you to decide obviously

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but we've looked into your concerns about time, fuel costs and car-lease distance limits

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and by the looks of it, you won't really bump up against any of them, and you definitely won't have to rot on campus for 12 hours at a time

strong flax
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hmm ok

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thx ann

final saddleBOT
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@strong flax Has your question been resolved?

final saddleBOT
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whole halo
#

<@&268886789983436800> @patent spire

final saddleBOT
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boreal smelt
final saddleBOT
boreal smelt
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how do I solve this?

terse crypt
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gp?

lime crest
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geometric series

terse crypt
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r = -tan^2 x

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i think

lime crest
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(since tan^2x < 1 in the given interval)

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who the hell writes 1 + 2 + ...infinity though

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never seen thst before

terse crypt
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is ... infty even a legit notation 😭

boreal smelt
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how did I not see it😭😭😭

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$\int^{\pi/2}_{0}\frac{dx}{(a^2sin^2x + b^2cos^2x)^2}$

soft zealotBOT
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Prathmesh

boreal smelt
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I tried by multiplying sec^2x in both numerator as well as denominator

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and then I substituted t=tanx

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this is what I got $\frac{1}{a}[\int^{\infty}_{0}\frac{dt}{(t^2 +b^2)^2}]$

soft zealotBOT
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Prathmesh

boreal smelt
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can anybody please help me with this integration

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a and b are constants

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@rustic sequoia

delicate sorrel
boreal smelt
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?

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.close

final saddleBOT
#
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stuck juniper
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Very cool way to do this

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I just worked it out

boreal smelt
stuck juniper
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And got pi/4ab(1/a-1/b)

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Is this right

boreal smelt
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just a sec

stuck juniper
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(1/b^2 -1/a^2)

boreal smelt
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yea

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you are correct

stuck juniper
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Cool

boreal smelt
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your answer is right

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how did you do this?

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I wanna know

stuck juniper
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Feynmann

boreal smelt
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is it a method?

stuck juniper
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First i took function of a

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I got a result

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Then function of b

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Got a result

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Added em up

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Got the answer

boreal smelt
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can you show?

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cuz i didn't understand

stuck juniper
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Yes

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@boreal smelt

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The first thing i got by simple integration

boreal smelt
stuck juniper
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<@&268886789983436800>

boreal smelt
final saddleBOT
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stuck juniper
final saddleBOT
stuck juniper
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Wrt to a variable

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Other the integrating variable

tired walrus
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with respect to to

supple mantle
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When the question is an answer

boreal smelt
stuck juniper
stuck juniper
opaque ember
boreal smelt
stuck juniper
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This is definitely one step above advanc

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I got the idea cause i had a similar question on my test

boreal smelt
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this question is in my dpp

stuck juniper
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Understandable

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I think u could by parts as well

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But cooler method

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🥸

stuck juniper
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Unless ur air 1

boreal smelt
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I am trying so hard to understand what you did 😭😭

stuck juniper
stuck juniper
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And b once

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Added them

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Sin^2+ cos ^2 is 1

boreal smelt
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but how did the integrand disappear ?

stuck juniper
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dx is still there

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Where ever it needs to be

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Solving habits

fast smelt
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you can differentiate with respect to whatever variable you want

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are you referring to the fundamental theorem of calculus?

boreal smelt
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and how did you write it directly as pi/2a^2b?

stuck juniper
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Wrt a

boreal smelt
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wouldnt it come with a negative sign?

stuck juniper
boreal smelt
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ohhhhh I finally got it mannnn

fast smelt
boreal smelt
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thanksssss

stuck juniper
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U could byparts

boreal smelt
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i well understand it now how you did it

stuck juniper
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But even that requires manipulation

boreal smelt
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btw can we introduce partial differentiation in any integration? Like does it affect the integration?

stuck juniper
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Should be continous

boreal smelt
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alright

stuck juniper
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Just watch some vids on it

boreal smelt
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can you recommend some?

stuck juniper
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Anything is fine

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Or even ask ur coaching sir

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My sir taught it

boreal smelt
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ohh

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okayyy

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thanks!

stuck juniper
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Also if want the by parts help

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Just multiply snd divide with the derivative of a^2sin^2x+b^2cos^2x

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Then by parts

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.close

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fleet hinge
#

Hello, first time here.
This is what I am struggling with.

thin cloud
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,rccw

soft zealotBOT
fleet hinge
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So far i have tried making a figure of sorts.

supple mantle
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Which question are you stuck with again?

fleet hinge
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Here @supple mantle

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I am sorry for not specifying.

supple mantle
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Ah

fleet hinge
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It is from the chapter quadratic equations. A basic introduction of sorts to it where only the formula is taught.

supple mantle
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Implicit differentiation

fleet hinge
supple mantle
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Well

fleet hinge
supple mantle
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Do you know what the shape you made is?

fleet hinge
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It is a triangle.

supple mantle
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Which type of triangle?

fleet hinge
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Right angled, since the tower must be standing perpendicular

supple mantle
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Exactly

fleet hinge
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I tried to go that way, got 20√5

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As the line that connects the initial points of the drone and the car

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At least as far as the question considers.

supple mantle
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What's the rest of the question?

fleet hinge
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At what distance from the base of the tower will the drone intercept the car

supple mantle
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Did you take trigonometry?

fleet hinge
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A drone is hovering at the top of a vertical tower that is 20 meters high. A car is moving in a straight line toward the base of a tower. At a certain moment, the car is 80 meters away from the base. At the same moment, the drone begins to descend in a straight line to intercept the car. Assuming the drone and the car are moving at the same constant speed, at what distance from the base of the tower will the drone intercept the car.

fleet hinge
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Specific angles like 0, 30, 45,60 and 90

supple mantle
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So just using pythagoras

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Well we don't really need to use much anyway

fleet hinge
supple mantle
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The triangle's base is 4 lots its height

fleet hinge
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Yes

supple mantle
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That's the slope of the straight line the drone will travel in

fleet hinge
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So, like the graph.

supple mantle
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Yea

fleet hinge
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x/4x?

supple mantle
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Mhm

fleet hinge
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okk.

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But neither of them are still, the drone must constantly change its path to intercept the car somewhere, right?

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And they both have a constant speed

supple mantle
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Well as the car gets closer to the tower, the drone's direction will become more vertically downwards

fleet hinge
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Yes.

supple mantle
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Wait

fleet hinge
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But, we aren't taught how to connect graphs with quadratic equations

fleet hinge
supple mantle
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$(80-vt)^2 + 20^2 = (20\sqrt{17}-vt)^2$

soft zealotBOT
#

VulcanOne

fleet hinge
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v is the change in time? or velocity?

supple mantle
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Velocity

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t is time

fleet hinge
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Why the 20²?

supple mantle
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From Pythagoras basically, we constructed this equation, but we kept in mind the constantly changing distance for the car and the drone

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The only distance that doesn't change is the tower's height

fleet hinge
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So we add it to the change in the car's movement?

supple mantle
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Wait hmm

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$(80-vt)^2 + (20-v_y t)^2 = (20\sqrt{17}-vt)^2$

soft zealotBOT
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VulcanOne

fleet hinge
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I don't really get it but thanks a lot. I will try to figure it out.

supple mantle
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$-40v_y t +v_y ^2 t^2 = 40(\sqrt{17} -4) vt$

soft zealotBOT
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VulcanOne

supple mantle
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That's the most I can come up with

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Atm

final saddleBOT
#

@fleet hinge Has your question been resolved?

final saddleBOT
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tardy hamlet
#

YOLO just need to ask if I’m going the right way

tardy hamlet
tired walrus
#

$\frac{2}{5} \cdot 10 \neq 8$ so i am afraid even your first line is mistaken

soft zealotBOT
tired walrus
#

that and the letter x seems to have vanished somewhere?

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dunno what's up w that.

final saddleBOT
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@tardy hamlet Has your question been resolved?

south harbor
#

Can some one help W 20

craggy plank
south harbor
craggy plank
#

and click on "follow category"

dusky shadow
#

,rccw

soft zealotBOT
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lyric moat
#

Was this solved right?

final saddleBOT
rocky tusk
lyric moat
rocky tusk
#

it looks like you wrote y/y

rocky tusk
lyric moat
rocky tusk
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where is y’ coming from?

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this is what i see

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$y = e^{2x + 3}$

lyric moat
soft zealotBOT
lyric moat
rocky tusk
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so why are you doing y’/y?

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logarithmic differentiation?

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just use the chain rule

lyric moat
rocky tusk
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🤔

lyric moat
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I am tweaking aren't I

rocky tusk
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left side is y’, right side is 2e^{2x + 3}

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multiply by the derivative of 2x + 3, which is just 2

lyric moat
#

FUCK

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YOU ARE RIGHT

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thanks bro

final saddleBOT
#

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hollow plover
#

can anyone help me solve this economics questionn

craggy plank
night raft
#

!da2a

final saddleBOT
#

No need to ask “Can I ask…?” or “Does anyone know about…?”—it’s faster for everyone if you just ask your question! See https://dontasktoask.com/

ripe jewel
#

!da2a

final saddleBOT
#

No need to ask “Can I ask…?” or “Does anyone know about…?”—it’s faster for everyone if you just ask your question! See https://dontasktoask.com/

ripe jewel
#

damn MxRgd's lightnign fingers beat mine

hollow plover
#

not sure how to solve for the change in producer revenue

final saddleBOT
#

@hollow plover Has your question been resolved?

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tall kindle
#

I have no answer key but I just wanted to double check that the answer is A and not B right?

kindred flicker
#

When speak spanish 😭💔

tall kindle
#

but it's two positive roots and one negative no?

loud sundial
# void ivy No sorry it's A

The given graph is shifted down by some amount. If we consider shifting the graph upward until the turning point below the x-axis is a double root, then the root with multiplicity 2 is positive.

coarse turtle
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Option A

tall kindle
#

ty

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.close

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loud sundial
final saddleBOT
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quasi plume
final saddleBOT
quasi plume
#

how do you do these?

fallen vigil
#

what is taylor series

quasi plume
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P_n(x) = bla bla bla

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huh

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what's the first step with problems like this?

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lets just choose 49 for example. take the limit I assume

rocky tusk
rocky tusk
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and do the algebra

quasi plume
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oh that's it?

rocky tusk
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yes

quasi plume
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I shouldnt try to evaluate the limit first?

rocky tusk
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the whole point is to do it with taylor series

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try the first one and it should be clear

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cos(x) = 1 - x^2/2 + x^4/24 - x^6/720 + …

quasi plume
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okay

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so I did it and got

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x^4/24 - x^6/720 + …

rocky tusk
#

/x^4

quasi plume
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right

rocky tusk
#

so what does that give you

quasi plume
#

lim x to 0 (x^4/24 - x^6/720 + …) / x^4

rocky tusk
#

no but more simplification

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divide each term in the numerator by x^4

quasi plume
#

okay

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lim x to 0 (1/24 - …) ?

rocky tusk
#

yes

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which is

quasi plume
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1/24?

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lemme write out the other term also

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lim x to 0 (1/24 - x^2/720 + …) ?

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oh

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x to 0 i'm dumb

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I thought it was inf

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okay bettt this is light

rocky tusk
#

yep

quasi plume
#

big ups knief, thanks

#

.close

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rigid nacelle
#

Increasing(Why does this mean above the X-axis?): (0, 2) U (4,6) U (8, inf)
Decreasing: (2,4) U (6,8)

Local Max: 2
Local Min: 4, 8

Concave Down: (0, 3)
Concave Up: (3,6) U (6, inf)

Inflection: 3

rigid nacelle
#

Is this right and how would I sketch it based on the results?

rocky tusk
rigid nacelle
#

Ah, ok

rocky tusk
#

you can think of f' > 0 as f has positive slope

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so its increasing

rocky tusk
#

you sort of just ignored it

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local max/min can occur where f is not differentiable

rigid nacelle
#

On which?

rocky tusk
#

not just at points where f' = 0

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for example, |x| has a local minimum at x = 0

rigid nacelle
#

I thought if it crosses the X-axis then it's will be an local max/min

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but 6 tping between the X-axis also counts?

rocky tusk
#

although |x| is not differentiable there

rocky tusk
#

but it doesn't exhaust all possible situations in which f has a local max/min

rocky tusk
#

,w graph |x|

rocky tusk
#

clearly not differentiable at 0 since the slope from the left doesn't agree with the slope from the right of 0

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however, it is a local minimum and in fact a global minimum

rigid nacelle
#

Why though?

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Is it because at 0, it changes directions? (goes from decreasing to increasing)

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but I thought that was an infleciton

rocky tusk
#

using the limit?

rigid nacelle
#

Nope

rocky tusk
#

$f'(a) = \lim_{x \to a} \frac{f(x) - f(a)}{x - a}$

soft zealotBOT
rocky tusk
#

never seen this?

rigid nacelle
#

I thought it was

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

rocky tusk
#

its an equivalent definition

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this gives the derivative at a point

rigid nacelle
#

Ah

rocky tusk
#

if you'd like, just substitute h = x - a then as x -> a, h -> 0 and f(x) = f(h + a) and so it becomes f(a + h) - f(a)/h

rocky tusk
#

now you should hopefully remember that if the limit from the left doesn't agree with or equal the limit from the right then the limit doens't exist yes?

rigid nacelle
#

Yeah

rocky tusk
#

so in our example with |x| the difference quotient (just the f(x) - f(a)/x - a stuff) becomes 1 on the right but - 1 on the left of zero

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clearly 1 isn't equal to -1 so the limit doesn't exist

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and thus f is not differentiable at 0

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but its clear that |x| has a minimum at 0

rigid nacelle
#

So you can also count 6 as a local min?

rocky tusk
#

how did you determine its a min and not a max

rigid nacelle
#

It went from -1 to 1

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neg to pos = min
pos to neg = max

rocky tusk
rigid nacelle
#

|x|

rocky tusk
#

or in |x|?

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6 is not a local min for |x|

rigid nacelle
rigid nacelle
#

It's why 0 is the local min

rocky tusk
#

yea 0 is a local min because there is an interval around 0 so that all points in the interval are above or equal to f(0)

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and in fact its a global minimum

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meaning its the smallest y value for the entire domain

rigid nacelle
#

For 6, it's local max then?

rocky tusk
#

yes

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increasing before 6, decreasing after 6

rigid nacelle
#

This si much easier to understand lol

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but yeah I get it, thanks

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Last questin, how would I sketch it?

rocky tusk
#

do they mean f(0) = 0

rigid nacelle
rocky tusk
#

because clearly f'(0) = 3

rigid nacelle
#

This is the entire question

rocky tusk
#

i think they mean f(0) = 0

rigid nacelle
#

I don't know, I am just a humbly confused student

rocky tusk
#

assume they mean f(0) = 0

rigid nacelle
#

Sure

rocky tusk
#

then just do interval work

#

you could just see that this looks like cosine

#

and deduce that f must be a sine wave from 0 to 6

rigid nacelle
#

Is just doing sin to cos enough?

rocky tusk
#

idk what you mean

rigid nacelle
#

Is it enough to just to sine wave from 0 to 6

rocky tusk
#

but what about after 6?

rigid nacelle
#

THat's my question lol

rocky tusk
#

looks almost like a parabola so it doesn't really matter that much so long as you capture the increasing/decreasing behavior and concavity

rigid nacelle
#

.close

final saddleBOT
#
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final saddleBOT
#
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spiral dock
#

i need help with this question

final saddleBOT
spiral dock
#
  1. g(t) = 4cos^3(1-2t)
#

idk wat to do next

#
  1. cos(1-2t) -> -sin(1-2t)
grave axle
#

it's a chain rule question imo

#

first find the derivative of cos⁴() then derivative of cos() and then the (1-2t)

grave axle
#

and multiply the three of them together

#

(1) (2) and (3)

spiral dock
supple mantle
#

Right

grave axle
#

yes

spiral dock
#

then i multiply it all together/

grave axle
#

yeah try it

spiral dock
#

hm okay

supple mantle
#

Keep in mind you need to apply Power rule in the beginning

spiral dock
#

4cos^3(1-2t)-sin(1-2t)(-2)

supple mantle
#

Yep

#

Correct

spiral dock
#

-8cos^3(1-2t)-2sin(1-2t)

#

ermm i dont think i did that right

supple mantle
#

g'(t) = 8cos^3(1-2t)sin(1-2t)

spiral dock
#

oh

#

how isnt the 8 infront of cos a negative

supple mantle
#

Because of the -2 and -sin

#

The negatives cancel

spiral dock
#

okay can u help me w the next question

#

or do i ahjve to start a new channel

supple mantle
#

You can send it here

spiral dock
#

for this i start with the product rule which is (f)(g') + (f')(g)

supple mantle
#

Mhm

spiral dock
#

f' = 2x g' = -5cscx

supple mantle
#

Hmm

spiral dock
#

ngl i dont know how g' becomes that

supple mantle
#

Check g' again

spiral dock
#

yeahh i knew it

#

cot5x

supple mantle
#

What's the derivative of cot(x)

spiral dock
#

-csc

supple mantle
#

Only?

spiral dock
#

ya

#

o wait

#

-csc^2

#

:D

supple mantle
#

Yep

#

Now what's the derivative of cot(5x)?

spiral dock
#

5-csc^2

supple mantle
#

-5csc^2(???)

spiral dock
#

x?

#

oh 5x

#

-5csc^2(5x)

supple mantle
#

Nope

#

You forgot that you used chain rule

spiral dock
#

(x^2)(-5csc^2(5x)) + (2x)(cot5x)

#

oh

supple mantle
spiral dock
#

-5x^2csc^2(5x) + 2cot(5x)

#

final answeR ^

supple mantle
#

Ye

#

Correct

spiral dock
#

yess

#

im lowk understanding it now ty

#

first we do the derivatrive of the squareroot to get rid of it right

#

so it would be

#

1/2(r^2 + r / r^2)^-1/2

supple mantle
#

Yeah

spiral dock
#

then i can cancel out both the r^2 in the numerator and denominator right

supple mantle
#

1/[2 * \sqrt{(r^2 + r)/r^2}]

spiral dock
#

can u show that written if possible

#

nvm i see it

#

wait nvm i dont

supple mantle
#

Hm

spiral dock
#

so if the r^2 cancels out

#

would the remaining r be r/1

#

so sqrt 1 + r

supple mantle
#

$\frac{1}{2\sqrt{\frac{r^2 + r}{r^2}}}$

soft zealotBOT
#

VulcanOne

supple mantle
#

It'll be (1+r)/r

#

$\frac{1}{2\sqrt{\frac{r+1}{r}}}$

soft zealotBOT
#

VulcanOne

spiral dock
#

i dont get it lol

supple mantle
#

That's the derivative of the root

spiral dock
#

i thought we got rid of the root

supple mantle
#

We simplified what was in the root

spiral dock
#

1/2(r^2 + r/ r^2)^-1/2

supple mantle
spiral dock
#

ohh

spiral dock
#

finding the derivative of it all?

supple mantle
soft zealotBOT
#

VulcanOne

supple mantle
#

And take the derivative of that and multiply it with the whole thing

final saddleBOT
#

@spiral dock Has your question been resolved?

#
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quasi plume
final saddleBOT
quasi plume
#

can someone help with #65 please

drowsy epoch
#

which part

lean magnet
quasi plume
#

basically

drowsy epoch
quasi plume
#

I managed to figure out a I think

#

ln(1+x) = series 1^k * (-1)^(k+1) / k which is just (-1)^(k+1) / k

#

part b is kinda cooked

#

so for that I tried

#

idk what the point of the -ln(1/2) is

#

but I did - series x^k / k = - - series 1/2^(k)*k

#

answer is correct, I'm sure my methodology is wrong though

#

I got the extra - from the -ln(1-x)

#

and then I took x=-1/2

#

and moved the negative outside bc I felt like it

#

therefore you get series 1/2^(k)*k

coral thunder
#

Part (a) uses ln(1+x) rather than ln(1-x)

quasi plume
#

it's straight forward

#

part b is the weird one bc there's random negatives present now

#

I wrote the series for "b" as series (-x)^k / k

#

but idk if that's right

coral thunder
#

For part (c) you can write $\ln \frac{1+x}{1-x} = \ln(1+x) - \ln(1-x)$ and subtracts the corresponding terms of each series.

soft zealotBOT
coral thunder
#

And yes, your series for part (b) looks fine.

quasi plume
#

I did the work after knowing the answer so I molded it as I saw fit

quasi plume
coral thunder
#

Yes

quasi plume
#

okay cool

#

so part c now

#

do you mean for me to plug in these?

coral thunder
#

Right

quasi plume
coral thunder
#

Well, they aren't equal to one another. The series you want is given by subtracting one from the other.

quasi plume
#

okay so we end up getting

#

x-(x^(2)/2)+(x^(3)/3) - (-x - (-x)^(3)/2 ...)

#

$$x - \frac{x^2}{2} + \frac{x^3}{3} - \dots - \left(-x - \frac{(-x)^2}{2} + \frac{(-x)^3}{3} - \dots \right)$$

soft zealotBOT
#

Paul04

quasi plume
#

seem right?

#

wait

#

$\ln \frac{1+x}{1-x} = \ln(1+x) - \ln(1-x)$ is the same as $\ln \frac{1+x}{1-x} = \ln(1+x) +- \ln(1-x)$

soft zealotBOT
#

Paul04

quasi plume
#

so I can just directly do $$x - \frac{x^2}{2} + \frac{x^3}{3} - \dots + \left(x - \frac{(x)^2}{2} + \frac{(x)^3}{3} - \dots \right)$$

soft zealotBOT
#

Paul04

quasi plume
#

right?

coral thunder
#

Right

quasi plume
#

okay so the resulting series is just gonna be

#

plus

coral thunder
#

That's right

quasi plume
#

denominators are the same so we can just add and get series [(-1)^(k+1)*2x^k]/k

coral thunder
#

The numerators aren't the same

quasi plume
#

oh

#

right

#

[(-1)^(k+1)*x^k]+[x^k]/k

#

I guess u can factor out x^k now if that helps

coral thunder
#

Yep

quasi plume
#

[ x^k * ((-1)^(k+1) + 1) ] / k

coral thunder
#

Yep. You could leave it like that, or check behaviour for odd & even k.

quasi plume
#

oh cool, that wasn't too bad

#

what does part d mean?

coral thunder
#

In part (e) they probably want you to only evaluate terms with nonzero coefficients.

quasi plume
#

okay

coral thunder
#

Oh, you want $\ln 2$ and have a series for $\ln \frac{1+x}{1-x}$. So you want $x$ such that $\frac{1+x}{1-x} = 2$.

soft zealotBOT
coral thunder
#

Have to go sorry, hope that's helped and maybe someone else can help more if needed.

quasi plume
#

sounds good, thanks so much!

#

.close

final saddleBOT
#
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#
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timber plume
#

I need help with 11. b)

final saddleBOT
timber plume
#

we were taught

#

that we cannot deal with

#

-1 exponents

#

because the denominator would be 0

#

if we tried integrating it

#

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

vital crag
#

if f(x) is even, then the integral of -1 to 1 of f(x) can be expressed in terms of the integral from 0 to 1 of f(x)

tired walrus
#

your teacher said, verbatim, "we cannot deal with -1 exponents"?

#

that aside though there is in fact no need to break your back with any integration at all here, as riemann said

timber plume
tired walrus
#

ok but this rule is entirely inapplicable here.

proper dagger
#

um, that's a quadratic in the denom anyway

tired walrus
#

that's precisely why the rule is inapplicable.

proper dagger
#

yea pointing it out to OP

tired walrus
#

yeah i guess when i say it there's like a debuff to comprehensibility or something

proper dagger
#

i didn't mean it that way, sorry if it came across as such

tired walrus
#

consider this

#

you've shown that 1/(x^2+1) is an even function

#

that means its graph is symmetric across the y-axis

#

what does that let you say about the green and blue areas as shown in my pic?

timber plume
#

same area

tired walrus
#

ok, do you see how to express $\int_{-1}^1 f(x) \dd{x}$ in terms of $\int_0^1 f(x) \dd{x}$ now?

soft zealotBOT
timber plume
#

but

#

don't we need to add a constant

#

of 2

#

before the integral

tired walrus
#

adding that constant is your job. you're not trying to say i omitted it by mistake, are you?

timber plume
#

I really thought

#

you missed a 2

pliant shore
tired walrus
#

i didn't miss shit, i said "express <this> in terms of <that>"

#

i didn't put any equals sign or do the expressing

#

that was deliberate because i wanted YOU to do it

vital crag
#

the last time ann left out a factor of 2, it was last century

tired walrus
timber plume
tired walrus
#

your op literally \textbf{asks for} $\int_{-1}^1 f(x) \dd{x}$.

soft zealotBOT
timber plume
#

yeah but then how will we integrate the integrand?

tired walrus
#

... you don't, not in this question.

#

the whole POINT was:
\begin{itemize}
\item they give you the value of $\int_0^1 f(x) \dd{x}$ for free
\item they ask for the value of $\int_{-1}^1 f(x)\dd{x}$
\item you need to find a link between the two and then use it
\end{itemize}

soft zealotBOT
vital crag
timber plume
#

ohh got it

#

pie/2

tired walrus
#

pi, not pie.

#

do not ever spell it as "pie".

timber plume
#

pi/2

timber plume
#

thanks

#

.close

final saddleBOT
#
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final saddleBOT
#
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jagged flare
final saddleBOT
jagged flare
#

$A,B,C,D,E,F$ are on a circle, $P,Q,R$ are the intersections of $AD$ and $BE$, $AD$ and $CF$, $BE$ and $CF$. If $AP=21$, $CQ=13$, $ER=35$, and $PQR$ is an equilateral triangle, then find $BP+DQ+FR$

soft zealotBOT
#

ihave<skissue>

jagged flare
#

ignore the 60

#

im confused, how do you do this? im guessing maybe poap? but how do you pull it

robust mulch
#

honestly my first guess is to let the equilateral triangle have side length 0

#

so you have three lines that intersect with 60deg angles

#

kinda stuck from there

#

worst case you can coordbash

#

just a guess but it may be 59

#

69*

#

theres probably some weird property about equilateral triangles and circles

final saddleBOT
#

@jagged flare Has your question been resolved?

coral thunder
#

One thing that occurs to me is that if you take a line parallel to AD, then the length of AP and DQ change by the same amount.

#

Likewise BP and QC

obtuse epoch
#

there's a symmetry

coral thunder
#

So you can choose the parallel line with Q=D=C, and then do the same for A=B=P

obtuse epoch
#

something like this ig AP+CQ+ER=BP+DQ+FR.

coral thunder
#

Yes, those transformations preserve (AP+CQ+ER)-(BP+DQ+FR).

#

And the final result has ER=FR

#

But there's probably something nicer and more rigorous.

obtuse epoch
#

21+13+35=69 deg

coral thunder
# jagged flare what?

If you imagine "sliding" one line of the equilateral triangle in and out to get different intersection points.

#

If you move the line outward, then AP and QD get longer by the same amount as each other, and BP and CQ shorter by the same amount as each other.

#

ER and FR don't change.

#

So the diagram with the larger triangle has the same value for (AP+CQ+ER)-(BP+DQ+FR).

obtuse epoch
#

if you rotate it then P becomes Q and Q becomes R and 1 more

jagged flare
#

does the expanding/contraction cancel eachother out?

vital surge
# jagged flare

a = AP, b = BP, c = CQ, d = DQ, e = ER, f = FR

power of a point:
(s + d)a = (s + e)b
(s + a)d = (s + f)c
(s + b)e = (s + c)f

rearrange:
(a - b)s = be - ad
(d - c)s = cf - ad
(e - f)s = cf - be

(1) - (2) + (3):
a + c + e = b + d + f = 69

jagged flare
#

i see, thank you guys!

#

.solved

final saddleBOT
#
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coral thunder
#

Oh yes that's a nicer one 🙂

final saddleBOT
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safe cradle
#

16*55 please

final saddleBOT
tired walrus
#

<@&268886789983436800> troll?

safe cradle
#

I got 28

tired walrus
safe cradle
fallen geyser
#

Don't use help channels for troll questions, thank you.

#

.close

final saddleBOT
#
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little finch
#

Find the coefficient of x^10 in the expansion of (1 + x^2)^20

proper dagger
#

oh boy. looks like a long day of binomial expansion with pascal's triangle?

little finch
#

yes

desert mantle
#

(not like you need to compute the entire triangle)

#

(and you could just compute the binomial coefficient with the factorial def)

#

(or maybe its even enough to just write down the binomial coefficient itself)

proper dagger
#

then that's out of my league

ivory bear
lucid nymph
#

you can use binomial general term

ivory bear
little finch
ivory bear
#

in the end my and @lucid nymph 's approaches are same

lucid nymph
#

$T_{r+1}=\binom{n}{r}x^{n-r}y^r$

soft zealotBOT
#

ImOakley

little finch
#

k

proper dagger
#

huh. looks remarkably like Bernoulli trials

tired walrus
little finch
#

x to the power 2r so r = 5 ?

tired walrus
#

r=5 indeed

proper dagger
#

fair

little finch
#

ok got it 20 c 5

#

Hey I've got another one

sour zealot
#

ok!

little finch
desert mantle
#

,rotate

soft zealotBOT
desert mantle
#

wrong pic?

little finch
#

naah the question below

lucid nymph
#

you mean the sum to 20 thing?

little finch
#

yes

desert mantle
#

thats an expression

lucid nymph
#

whats the question

desert mantle
#

not a question

little finch
#

help tho ;-;

sour zealot
#

what do you need help with ;-;

lucid nymph
#

im confused are u supposed to express the sum?

tired walrus
#

!xy

final saddleBOT
#

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.

little finch
#

i showed the picture

lucid nymph
#

that cant be the original question

little finch
#

that is

#

ig they want the sum

lucid nymph
#

are you able to take a screenshot of something?

little finch
tired walrus
#

we do not understand WTF the question is asking

lucid nymph
#

where is the question from

#

how was it given to you

bold turtle
little finch
#

its asking the sum

#

i suppose

desert mantle
#

pull out a factor of 2

late bolt
#

Is it this?

little finch
little finch
#

use the general term then?

desert mantle
#

2*2^(20-r)

little finch
#

ok got it thanx

#

.close

final saddleBOT
#
Channel closed

Closed by @little finch

Use .reopen if this was a mistake.

little finch
#

.reopen

final saddleBOT
#

solid notch
#

do you have a question?

proper dagger
#

if you have, please send it

little finch
#

yes

#

wait a minute im taking picture

#

The empty space has the summation symbol

final saddleBOT
#
What step are you on?
1. I don't know where to begin.
2. I have begun but got stuck midway.
3. I got an answer but I was told that it's wrong.
4. I got an answer and would like my work checked.
5. I have a question about someone else's work/solution.
6. I have completed the problem and don't need help anymore. Thank you.
7. None of the above
little finch
sour zealot
#

could you show your work?

little finch
#

word?

proper dagger
#

work

little finch
#

its quite messy i did it in rough i rewrote it as 1/n(1+k/n+(k/n)^2
ig its riemann summ of 0,1

tired walrus
#

for the future, btw:

#

!1q

final saddleBOT
#

It is suggested that you limit yourself to one question per help channel, opening a new one once your original question is answered and your original channel has been closed. This is to make your channel easier to follow for potential helpers and can bring attention to the fact that your question has changed.

tired walrus
#

and also ^ for exponents

little finch
tired walrus
#

shift 6

little finch
#

ok thx

#

so will i recieve help tho?

proper dagger
#

i don't see a question

little finch
#

the empty space is summation idk y it glitched

little finch
proper dagger
#

yes

little finch
#

ok

little finch
#

sed

little finch
#

.close

final saddleBOT
#
Channel closed

Closed by @little finch

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final saddleBOT
#
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Ask your math question in a clear, concise manner.
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past cargo
final saddleBOT
past cargo
#

not math

#

but can someone help

solid notch
#

give input on what you think

past cargo
#

i think it will affect momentum because mass is changed

flint saffron
#

Hello i have to do a decomposition in fourier's series of Bcos(wt)cos(phit) so i said that it is B/2*(cos((w+phi)*t+cos((w-phi)*t)) ( idk if it is correct but it seems logical, fourier's decomposition is transforming an expression to the sum of cosins and sin, however it asks to draw the graph of fourier. I looked it up online and it would seem that i have to draw triangles but I do not get it. May someone explain it to me ? I am french so the question I have of my book is french but i do not know the method.

final saddleBOT
final saddleBOT
solid notch
#

sniped

thin cloud
#

that was fast

proper dagger
#

i barely typed

flint saffron
night raft
#

lol

night raft
meager mirage
solid notch
past cargo
#

is momentum not mass x velocity

night raft
#

yes

past cargo
#

mass increases

meager mirage
past cargo
#

oh true

lucid nymph
#

conservation of momentum is one of the fundamental laws

meager mirage
#

It only changes if net external force / thrust is applied

past cargo
#

so does it do nothing then, because they act perpendicular to each other. like its moving horizontal and that thing is being dropped vertically

lucid nymph
#

no

#

the mass of the truck increases

#

so the velocity decreases

#

conservation of momentum applies in each direction

#

so the fact that they are perpendicular doesnt matter

past cargo
#

ok so no change of momentum then?

lucid nymph
#

impossible

meager mirage
night raft
meager mirage
#

Use energy

lucid nymph
#

this isnt a question about energy

past cargo
#

if mass increases and velocity decreases then its the same

meager mirage
#

Mgh = 1/2(m+M)v^2

past cargo
#

wdym

solid notch
#

the cart is already at the runaway

#

read the question again

meager mirage
meager mirage
solid notch
#

he asked 2.4 , your suggestion was prol relevant for 2.1, 2.2

meager mirage
#

Mb

past cargo
#

so what happens then

solid notch
#

pricisely

meager mirage
#

Yeah velocity decreases

solid notch
past cargo
#

what about for the collected water

lucid nymph
#

thats what were talking about

#

the water adds mass to the truck so the truck has to slow down

solid notch
past cargo
#

yes we discussed effect on the truck

#

now what about the water

lucid nymph
past cargo
lucid nymph
#

no you dont understand

#

momentum is conserved in each direction

#

the rain has no horizontal momentum

past cargo
#

does it not convert

lucid nymph
#

and in the vertical technically momentum is still conserved its just it comes in the form of going into the whole earth and giving it a change in velocity so tiny its literally negligible in every sense

past cargo
#

it falls and hit the truck, the tuck is moving so the water also moves in the truck

#

so vertical to horizontal

lucid nymph
#

?

past cargo
#

so a increase in momentum

lucid nymph
#

like i said momentum is conserved in each direction

#

you cant bring momentum from the vertical to the horizontal

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if two balls hit off each other they still retain the exact same speeds in the directions perpendicular to where their centers align

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because its only the direction they impact along that is affected

past cargo
#

yh i see

#

thanks for the help

#

.close

final saddleBOT
#
Channel closed

Closed by @past cargo

Use .reopen if this was a mistake.

#
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ember escarp
#

how to get the rational equation of 1/x = 2/3x-1?

terse crypt
#

Wdym ‘get’

ember escarp
#

oh what i mean is what is the rational equation

#

sorry, wrong sentence

terse crypt
#

Do u mean

#

‘How do I solve this rational equation?’

ember escarp
#

yes

delicate sorrel
terse crypt
#

Eliminate the denominators first

#

And note where x are undefined

ember escarp
#

what I have so far is I found the lcd

#

then i tried multiplying both sides

#

and from there, im lost

delicate sorrel
#

$/fract{1}{x}/ = /frac{2}{3x-1}$

delicate sorrel
coarse mantle
ember escarp
coarse mantle
#

you'll get $2x = 3x-1$

soft zealotBOT
#

Bakoles

severe canyon
#

I have a hunch that we are solving a different expression

#

!original

final saddleBOT
#

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.

delicate sorrel
#

You can its allowed

ember escarp
#

can u show me how?

delicate sorrel
#

I mean by inverse like 1/x become x

#

And 2/3x+1 becomes 3x+1/ 2

ember escarp
#

aren't we supposed to look for the lcd?

delicate sorrel
#

Youll have x= 3x + 1 /2

delicate sorrel
coarse mantle
soft zealotBOT
#

Bakoles

ember escarp
#

cuz i know u find the lcd then multiply it both sides then solve and check the solution

#

I understand the instructions, its just that I can't comprehend on how to solve it

#

or the steps

coarse mantle
#

look, get rid of the fraction 1/x

#

how?

#

multiply it by x

#

you get $x\cdot\frac{1}{x} = x\cdot\frac{2}{3x-1}$

soft zealotBOT
#

Bakoles

coarse mantle
#

do you see it now?

ember escarp
#

mhmm

coarse mantle
#

can you multiply them?

#

what do you get

ember escarp
#

wouldn't be just the same cuz x = 1?

coarse mantle
#

i mean yes, x = 1

#

wait

#

what was your question?

#

didn't you need to find x?

ember escarp
#

yes

coarse mantle
#

okay great you found it

#

x = 1

ember escarp
#

oh

#

i have another one tho, its much different

#

x-2/2x+4 = 1/5

coarse mantle
#

did you try anything so far

ember escarp
#

still the same

#

stuck in multiplying both sides

#

thats what im having a hard time

coarse mantle
#

use the butterfly technique

ember escarp
#

does it apply to any equation?

coarse mantle
#

see this example:
if a/b = c/d
then ad = cb

#

$5(x-2) = 1(2x+4)$

soft zealotBOT
#

Bakoles

coarse mantle
#

can you solve it now?