y = 3x + 2,y'= 3
y = x^(-2),y'=-2*x^(-3) = -2/x^3
y'|(x=-1) = -2/(-1) = 2
y = x^(1/2) y'= (1/2)x^(-1/2)
f'(4) = (1/2)4^(-1/2) = 1/4