If f (x) = ax - (a + 1) ln (x + 1), a is greater than or equal to - 1, how to calculate its derivative? I don't know how to calculate derivative?

If f (x) = ax - (a + 1) ln (x + 1), a is greater than or equal to - 1, how to calculate its derivative? I don't know how to calculate derivative?

f'(x)=a-(a+1)/(x+1)