# Thread: definite integral

1. ## definite integral

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..FIng g(u) ,a,b and the integral

2. $\int_{\frac{\pi}{6}}^{\frac{\pi}{2}} \frac{cosx}{sin^7x}dx = \int_{sin(\frac{\pi}{6})}^{1} \frac{1}{u^7}du$

by using the substitution u = sin(x)

3. Originally Posted by sss
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$\int_1^{e^8} \frac{dx}{x\sqrt{lnx}} = \int_0^{8} \frac{du}{\sqrt{u}}$

using the substitution $u =ln(x)$

I think you could do the other integral by parts