Question

关于函数的单调性问题!设函数f(x)=(x+a)/(x+b)(a＞b＞0),求f(x)的单调区间,并证明f(x)在其单调

Answer 1

f(x)=(x+a)/(x+b)

f(x)=(x+a)/(x+b)=【x+b+a-b]/(x+b)=1+(a-b)/(x+b)

(a-b)>0 (a-b)/(x+b)为减函数

f(x)=(x+a)/(x+b)为减函数