# Evaluate the definite integral

1. Oct 12, 2006

### sapiental

the definite integral:

from a = (-pi/2) to (pi/2) f(((x^2)(sinx))/(1+x^6))dx

this is the way it seems most logic to me to set it up using substitution:

u = x
du = dx

from a = (-pi/2) to (pi/2) f(((u^2)(sinu))/(1+u^6))du

= (((-cos(u))(1/3u^3))/(u+1/7u^7))+C

I know how to evaluate it from here, I just need some feedback on my substitution setup.

2. Oct 12, 2006

### neutrino

That sort of substitution does nothing but change the letter denoting the variable.

3. Oct 12, 2006

### shmoe

Try sketching the graph. Notice anything?

I'm worried about what "Take the square root of the numerator and denominator" could possibly mean? I don't see how your substitution gives what you claim it gives either.

4. Oct 12, 2006

yeah, I made a mistake. I took the integral of the square root of the function instead of the actual function.