means compplete the square on one side
basically get into form [tex]f(x)=a(x-h)^2+k[/tex]
ok, group x terms
[tex]p(x)=(-8x^2-64x)[/tex]
factor out linear coefient (-8)
[tex]p(x)=-8(x^2+8x)[/tex]
take 1/2 of the linear coefient and square it
8/2=4, 4^2=16
add positive and negaitve of that inside parntheaese
[tex]p(x)=-8(x^2+8x+16-16)[/tex]
factor perfect square
[tex]p(x)=-8((x+4)^2-16)[/tex]
expand
[tex]p(x)=-8(x+4)^2+128[/tex]
in vertex form it is [tex]p(x)=-8(x+4)^2+128[/tex]
