Question

What is `int (4x^3 + 5)/(x^4 + 5x) dx`?

Answer 1

`ln|x^4+5x|+c`

Explanation:

`int(f'(x))/f(x)dx=ln|f(x)|+c`

`f(x) = x^4+5x`
`f'(x) = 4x^3+5`

Hence the integral above follows the formula.