Tom N. answered 02/20/21
Strong proficiency in elementary and advanced mathematics
To evaluate the integral of x2 (x3+1)dx let x3 +1 = u so that du = 3x2dx where x2dx = du/3. So the integral becomes ∫u3du/3 +C and this becomes u4/12 +C. Replacing u the integral is (x3 +1)4/12 +C which is answer B.