math
posted by Melissa .
The sum of two numbers is 16 . What is the largest possible product between these numbers

1 + 16
2 + 14
3 + 13
4 + 12
5 + 11
6 + 10
7 + 9
8 + 8
Which of those produce the greatest product? 
y = x (16x) = 16x  x^2
dy/dx = 0 at max = 16  2x
so
x = 8
8*8 
or find vertex of that parabola (y = 16xx^2) if you do not know derivatives.
x^2  16 x = y
x^2  16 x + 64 = y+64
(x8)^2 = (y+64)
x = 8 
eight