Question

The pair of numbers whose difference is 18 and whose product is as small as possible is? The minimum product is?

Answer 1

Assume the bigger number is x, since the difference is 18, another one should be x - 18

So the product will be x(x-18) = x^2 - 18x = (x-9)^2 - 81

Since the minimum of (x-9)^2 is 0, then the minimum of the product is -81