Two numbers have a sum of 72. What is their product if it is a maximum?

Answer 1

let the two number be x and 72-x
let P be their product
P = x(72 - x) = -x^2 + 72x

the x of the vertex is -72/-2 = 36
then P = 36(72-36) = l6^2 = 1296

Answer 2

72-x = 72x