57. Let f : R → R be defined by
f(x)= {x+2 (x ≤ -1)
{ x2 (-1 ≤ x ≤1)
{2 - x (x ≥ 1)
Then value of f (-1.75) + f (0.5) + f (1.5) is
60. Which of the following sets is a null set ?
I. X = {x | x= 9, 2x = 4 }
II. Y = {x | x= 2x.x ≠ 0 }
III. Z = { x | x-8 = 4 }