
Doug C. answered 03/23/24
Math Tutor with Reputation to make difficult concepts understandable
This is a u-sub.
Let u = tan x
du = sec2(x)dx
Integral becomes:
∫ (1+u3)du
Take it from there remembering to replace u with tanx and add a constant of integration.

Doug C.
Yes, here is a verification. Use the technique here to check your work on other indefinite integrals, i.e. f(x) = integrand, F(x) = your answer, F'(x) should match the integrand. desmos.com/calculator/lni20loblx03/25/24
Josh D.
so will the answer be tanx +tan^4x/4 + C03/24/24