西安毛子律技枝大学=ax+b,x<1f(x)=3(a+ b + 1),x=1x2,x>1x<1时, f'(x)=a, x>1时,f'(x)=2xf'(1) = 2 a=2, b=-1,x≤1[2,f(x)=2x,x>177  a = 2, b = −1, f (1) = 2       = 2 , 1 2 , 1 ( ) x x x f x f (x) = ax + b , x  1 ( 1), x = 1 2 1 a+ b + , x  1 2 x x  1时, f (x) = a , x  1时，f (x) = 2x