calculus help me

Question

Evaluate the integral

` \int x^5 (x^6 - 4)^(20) dx `

by making the substitution ` u = x^6 -4 `.

__________________  + C

NOTE: Your answer should be in terms of x and not u.

Answer 1

The suggested substitution means du=6x⁵ dx so that the integrand becomes

(1/6) u²⁰ du and the result is u²¹/126.

Now make the substitution back into the x variable, i.e. substitute x⁶-4 for u.

Answer 2