Square Deal

Learning Focus

Rewrite quadratics into vertex form $y=a(x-h)^2+k$ and read the vertex $(h,k)$.

Big idea

Completing the square turns $ax^2+bx+c$ into vertex form so you can graph by shifting a parent parabola.

Worked example

$y=x^2-6x+10=(x-3)^2+1$ has vertex $(3,1)$.

Takeaways

• $a>0$ opens up (minimum); $a<0$ opens down (maximum).
• Vertex is visible in vertex form without guessing.