Note: The π in the original question is a typo — the integral is ∫xn+1−xdx.
Factor x out of the denominator:
xn+1−x=x(xn−1)
So the integral becomes:
∫x(xn−1)dx
Divide both the numerator and denominator by xn+1 (i.e., multiply by x−n−1x−n−1):
Denominator: x(xn−1)⋅x−n−1=x−n(xn−1)=1−x−n
Numerator: 1⋅x−n−1=x−n−1
So we get:
∫1−x−nx−n−1dx
We do this because the derivative of the denominator will match the numerator — setting up a clean substitution.
Let u=1−x−n
du=nx−n−1dx
x−n−1dx=ndu
Substituting into the integral:
∫u1⋅ndu
=n1∫udu
=n1ln∣u∣+C
Replace u with 1−x−n:
=n1ln∣1−x−n∣+C
Since 1−x−n=1−xn1=xnxn−1, we can write:
∫xn+1−xdx=n1lnxnxn−1+C