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use the fundamental Theorem of Calculus to find `d/(dx) int_(-3x)^(2x) e^(t^2) dt`  

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kathyyyyyy123 | Student, Undergraduate | Honors

Posted November 28, 2012 at 1:28 PM via web

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use the fundamental Theorem of Calculus to find

`d/(dx) int_(-3x)^(2x) e^(t^2) dt`

 

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mathsworkmusic | (Level 3) Associate Educator

Posted November 28, 2012 at 3:19 PM (Answer #1)

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We want `d/(dx) int_(-3x)^(2x) e^(t^2) dt`

Now `(int_a^b e^(t^2) dt)^2 = (int_a^b e^(x^2) dx)(int_a^b e^(y^2) dy) = int_0^((b-a)^2) e^(x^2+y^2) dxdy `

Converting to polar coordinates

`(int_a^b e^(t^2) dt)^2 = int_0^(2pi) theta d theta int_0^((b-a)^2) re^(r^2) dr = int_0^(2pi)(d theta)/2e^(r^2)|_0^((b-a)^2) = (theta/2e^(r^2)|_0^((b-a)^2))|_0^(2pi)`

`= pi e^(r^2)|_0^((b-a)^2) = pie^((b-a)^4)`

Therefore `d/(dx) int_(-3x)^(2x) e^(t^2) dt = d/(dx) sqrt(pi)e^(1/2(5x)^4) = (2)(5^4)x^3sqrt(pi)e^(1/2(5x)^4)`

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