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Mathematics 19 Online
OpenStudy (nincompoop):

favorite kind of calculus problem

OpenStudy (nincompoop):

OpenStudy (nincompoop):

I dont really need help :D

geerky42 (geerky42):

Cool.

OpenStudy (astrophysics):

Nin ain't pellet

OpenStudy (nincompoop):

laughing out loud

OpenStudy (nincompoop):

yeah. nin is NIN

OpenStudy (kainui):

Oh yeah, my kind of problem. Ok I'm gonna try to figure this one out now give me a few minutes...

OpenStudy (anonymous):

I remember looking at the solution manual for this one

OpenStudy (kainui):

I need to study cubics, quartic, and higher order polynomials more haha. I'm making progress but it's fairly slow but fun.

OpenStudy (kainui):

I think I figured it out. Tricky problem!!

OpenStudy (kainui):

Nope, I'm stuck. Hmm. Ok someone tell me if I'm going in the right direction or what: Basically I'm calling these two x values that have the height C on the curve as x_0 and x_1 So to be clearer, \[\LARGE 0<x_0<x_1\] To make the areas equal I set their integrals equal:\[\Large \int\limits_0^{x_0}Cdx-\int\limits_0^{x_0}2x-3x^3dx=\int\limits_{x_0}^{x_1}2x-3x^3dx\] I combined the cubic integrals on the right \[\Large \int\limits_0^{x_0}Cdx=\int\limits_{0}^{x_1}2x-3x^3dx\] and got:\[\Large Cx_0=x_1^2-\frac{3}{4}x_1^4\] Also, remember that since x_0 and x_1 fall on the curve and have the same height C, then I can plug them into the cubic from earlier before integrating to get: \[\Large 2x_0-3x_0^3=2x_1-3x_1^3=C\] So I do some clever substitution: \[\Large Cx_0=\frac{x_1}{4}(2x_1+C)\] But this really doesn't solve my problem after I solve for C I get:\[\Large C=\frac{2x_1^2}{4x_0-x_1}\] So I need to find some way to figure out more.

OpenStudy (nincompoop):

\[\int\limits_{a}^{b}[(-3x^3+2x)-c]dx=0\]

OpenStudy (nincompoop):

\[-\frac{ 3b^4 }{ 4 }+b^2-bc=0\]

OpenStudy (kainui):

What's a and b supposed to be?

OpenStudy (nincompoop):

pellet that's wrong

OpenStudy (nincompoop):

\[c = -3b^3 + 2b\]

OpenStudy (nincompoop):

a =0 @Kainui

OpenStudy (kainui):

And what's b? I am not seeing why this integral should be zero.

OpenStudy (nincompoop):

it has to be zero just the same when we setting up with the value for the y or straight line.

OpenStudy (kainui):

|dw:1405742145054:dw| label this with a and b.

OpenStudy (nincompoop):

right? then after we set that one up, we equate |dw:1405742156822:dw|

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