Question

Find the vertex of the parabola by completing the square.
x^2-6x+8=y
A. (–3,– 6)
B. (3,–1)
C. (–3,1)
D. (–1, 3)

Answer 1

\[
y=x^2-6x+8\\
y'= 2 x -6\\
2 x -6 =0\\
x=3\\
y= 9 -18 +8=-1\\
(3,-1)
\]

Answer 2

Now do it by completing the square.

Answer 3

\[
y=x^2-6x+8=y= x^2 - 6 x + 9 -9 + 8= (x-3)^2 -1
\]