Question

How do you graph y=-x(squared) + 8x

Answer 1

The 8 is your y intercept so
y=(0,8) then -x is actually -1x and the -1 is your slope, so its -1/1
so your first point is (0,8) and your second is 1 down and 1 over from that

Answer 2

\[y=-x^2+8x\] a parabola that opens down. looks like this
http://www.wolframalpha.com/input/?i=-x^2%2B8x