这个符合函数的求导
问题描述：
这个符合函数的求导
RT
（1）f(x)=((x-1)/(x+2)) +ln(x+1)
(2) f(x)=((x-1)/(x+a)) +ln(x+1)
答
(1)
f'(x) = ((x-1)/(x+2))' + 1/(x+1)
= ((x+2)(x-1)' - (x-1)(x+2)')/(x+2)^2 + 1/(x+1)
= 3/(x+2)^2 + 1/(x+1)
(2)
f'(x) = ((x-1)/(x+a))' + 1/(x+1)
= ((x+a)(x-1)' - (x-1)(x+a)')/(x+a)^2 + 1/(x+1)
= (a+1)/(x+a)^2 + 1/(x+1)