How to find the minimum or maximum value of y=8x(x+15)

Answer 1

The extrema occurs at average of the solutions.

The solutions are x=0 and x = -15

The average of them is x=-7.5

So 8(-7.5)( -7.5 + 15) =

8( - 7.5) ( 7.5) =

8( -56.25)

8( -56 + -.25) =

-448 + -2 =

- 450