50. Incorrect. The answer is false, not true. In general, integration by substitution is performed as follows: ∫f(x)dx = ∫u(du/dx)dx = ∫udu = F(u) +c. Therefore, set u=x³+1, then du/dx = 3x² and dx = du/3x². Substitute this into the integrand: ∫16x²(x³+1)dx = ∫15x²*udu/3x² = ∫5udu = 5*0.5u² + c = 2.5u² +c = 2.5(x³+1)² + c.