Please help?

Let F(a) be the area between the x-axis and the graph of y=x^2cos(x/4) between x=0 and x=a, for a>0 (consider the area to be negative if the graph lies below the axis).

Find the formula for F(a).

3 answers

We integrate by parts twice:
1)u=x^2, du=2xdx, dv=cos(x/4)dx, v=4sin(x/4)
2)u=8x, du=8dx, dv=sin(x/4)dx, v=-4cos(x/4)
The answer I have already sent.
Yes, you are right Thanks, I just found it! =)
what was the answer