Question 678514
The function is {{{-x^2 +8x -7}}}.  That means the function opens down and has a maximum value at x=(-b/2a) where a  = -1 and b =8.  Remember these functions are of the form ax^2 +bx +c<P>
x = -8/2(-1) = -8/-2 = 4.<P>
The y value when x=4 is -(4^2) +8(4) -7 = -16 +32 -7 = 9
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