Question

Whats the vertex form of y=x^2-20x+15

Answer 1

This looks like a parabola so:
y=x^2 - 20x + 15  -->  x^2 - 20x +15=y
(x^2 -20x)=y - 15  -->  (x - 10)^2=y - 15 +100  ( used complete the square)
(x - 10)^2=y + 85