1. The problem statement, all variables and given/known data find two numbers whose sum is 20 and whose product is a maximum. 2. Relevant equations the first number is X the second number is 20-x 3. The solution X(20-X)=0 -X^2+ 20x=0 x=-b/2a = -20/2(-1) = 10 20 - x =20 -10 = 10 the numbers are 10 and 10 i just dont get why / how you know to put x and 20 - x and why you would use the axis of symmetry to find the numbers and sry mods i posted originally in the wrong thread.