Using the method of substitution, I=integral from 1 to 4 of x^2(1+3x^3)^3 dx= integral from a to b of f(u) du

Question

u=

du= dx

a=

b=

f(u)=

The value of the original integral is I=

Answer 1

The substitution you need is u=1+3x³, then du=9x² dx.

You will need to multiply the integral by 9/9 and then your integrand becomes u³ du.