integrate the derivative of x^5
Let's differentiate: (x5)'
5x4
Let's integrate: ∫(5x4)dx
5·x55
5·x55 = 5x555x55 = x5
x5
Indefinite integrals are defined up to an additive constant C, so this yields: x5 + C
Answer:   x5 + C, where C is a constant