Question

If y=2x-2 , what is the minimum value of the product xy?
A. -16 B. -8 C. -4 D. 0 E. 2

Answer 1

z = xy = 2(x^2-x)
dz/dx = 0 at min = 2(2x-1)
x = 1/2
y = -1
xy = -1/2