Question

If a and b are negative integers such that a - b = - 2 , then what is the least possible value of ab ?

Answer 1

a-b = -2

a = b-2, so
ab = (b-2)b
This is a parabola with roots at 0 and 2, so the vertex is at b=1
So ab = (-1)(1) = -1
the parabola opens upward, so the vertex is its minimum value.