f(x)=integral[4,x^2] (1/4t^2-1)^15 dt

the only thing tripping me up here is the ^15.

i accidentally did the problem through without the ^15, but dont know where i should have used it anyway

i set x^2=u

so

=(1/4*u^2-1)^15(2x)

=(1/4*(x^2)^2-1)^15(2x)

=(1/4*x^4-1)^15(2x)

do i continue from here or did i make a mistake?