If f(x)= cases2+2x, & -1 x<0\ 1- x3, & 0 x 3 cases; g(x)= cases-x, & -3 x 0\ x, & 0<x 1 cases, then range of (f g)(x) is
- [0,1)
- [0,3)
- (0,1]
- [0,1]
Answer
(4) [0,1]
Solution
-3 x 0: g(x)=-x [0,3]; 0<x 1: g(x)=x (0,1]
∴ g(x) [0,3] always use f(u)=1- u3
(f g)(x)= cases1+ x3, & -3 x 0\ 1- x3, & 0<x 1 cases
[figure]
Values run from 0 (at x=-3) to 1 (at x=0), every value in between taken
∴ Range =[0,1]
Answer: (4)