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)

A, B, C, or D? Please explain :)

Answer 1

divide the number in front of x by 2 and then square it, then add and subtract that number into the equation

(-6/2)^2=9

x^2-6x+9-9+8

factor first three terms and add -9+8

y=(x-3)^2-1

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

so the vertex is (3,-1)

Answer 2

Thanks a lot :)