Question 168915
vertex form is y=a(x-h)^2+k, where (h,k) is the vertex


y=x^2-16x+56 __ subtracting 56 __ y-56=x^2-16x


completing the square by adding half of the x coefficient, squared __ y-56+(-16/2)^2=x^2-16x+(-16/2)^2


y-56+64=x^2-16x+64 __ y+8=(x-8)^2 __ subtracting 8 __ y=(x-8)^2-8


the vertex is (8,-8)