f(x) = INT[0,x^3] sin(t)dt

sin(t)dt = g(t)

f(x)	= G(x^3) - G(0)
f'(x)	= G'(x^3) * x^3' - G'(0) * 0'
f'(x)	= g(x^3) * 3x^2 - g(0) * 0
f'(x)	= sin(x^3^2) * 3x^2 - sin(0) * 0
f'(x)	= sin(x^6) * 3x^2