A:3
B:7
C:
D:
— Dirty water shouldn't be poured into rivers.
— _______. It will cause pollution.
已知函数f(x)=1+mx,且f(1)=2,
(1)求m的值;
(2)试判断函数f(x)在(0,+∞)上的单调性,并用定义加以证明.