Monday, October 26, 2015

calculus - Compute: $int_{0}^{1}frac{x^4+1}{x^6+1} dx$



I'm trying to compute: $$\int_{0}^{1}\frac{x^4+1}{x^6+1}dx.$$



I tried to change $x^4$ into $t^2$ or $t$, but it didn't work for me.



Any suggestions?



Thanks!



Answer



Edited Here is a much simpler version of the previous answer.



$$\int_0^1 \frac{x^4+1}{x^6+1}dx =\int_0^1 \frac{x^4-x^2+1}{x^6+1}dx+ \int_0^1 \frac{x^2}{x^6+1}dx$$



After canceling the first fraction, and subbing $y=x^3$ in the second we get:



$$\int_0^1 \frac{x^4+1}{x^6+1}dx =\int_0^1 \frac{1}{x^2+1}dx+ \frac{1}{3}\int_0^1 \frac{1}{y^2+1}dy = \frac{\pi}{4}+\frac{\pi}{12}=\frac{\pi}{3} \,.$$



P.S. Thanks to Zarrax for pointing the stupid mistakes I did...



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