Can someone help me out? I have been gone, and am trying to figure this out myself. Just start me?... what u, du, v, and dv equal? integrate 3(sin x)^-2 dx and integrate (x^4)(e^-x) dx Please, Id really appreciate it!
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Hello, Morgan82! Use a trig identity on the first one . . . $\displaystyle \int 3(\sin x)^{-2} \,dx$ We have: .$\displaystyle \int\frac{3\,dx}{\sin^2\!x} \;=\;3\int\csc^2\!x\,dx \;=\;-3\cot x + C $
For the second part you will use integration by parts 4 times. Use $\displaystyle u = x^4$ $\displaystyle dv=e^{-x}dx$ for the first iteration.
Last edited by lvleph; Nov 19th 2009 at 05:53 PM.
What is the integral of e^-x? Originally Posted by lvleph For the second part you will use integration by parts 4 times. Use $\displaystyle u = x^4$ $\displaystyle dv=e^{-x}$ for the first iteration.
Originally Posted by Morgan82 What is the integral of e^-x? You can use u-substitution for that; $\displaystyle \int \! e^{-x} \,dx = \int \! e^u \cdot \frac{du}{dx} dx$
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