f(x)={2x(0<=x<=1);
{-2/5x+12/5(1<x<=5).它的图像是折线OAB,其中O是原点,A(1,2),B(5,2/5).(1)直线l:kx-y-k+1=0过点C(1,1),它从CB转到CO时与y=f(x)的图像恰有两个交点,其他情况不满足题设。CB的斜率=(-3/5)/4=-3/20,CO的斜率=1,∴k的取值范围是[-3/20,1].(2)g(x)=xf(x)={2x^(0<=x<=1),∈[0,2];
{x(-2x/5+12/5)=(-2/5)(x-3)^+18/5,(1<x<=5),∈[2,18/5].∴g(x)的值域是[0,18/5].... |