Please let me know of any errors/wrong logic

f(x) = { |x| for -1 < x <=1 , 0 elsewhere

A)Determine Cumulative Distributin Function...

F(x) = { 0 for x < -1 , -0.5(x^2) for -1 <= x < 0 , 0.5(x^2) for 0 <= x <= 1, 1 for x >1

B)F(-0.25)

(-0.5)(-0.25)^2 = -0.03125

I thought that it should yield a positive value...

C)Pr(-0.25 <= X <= 0.5)

F(B) - F(A) = F(0.5) - F(-0.25) = (0.5)(0.5)^2 - (-0.5)(-0.25)^2 = 0.4375