Question

Which of the following is the vertex of the function?
y = x2 - 6x + 9 (Points : 4)

(3, 0)
(-3, 36)
(4, 1)
(1, 4)

Answer 1

use the discriminant to find the x value of the vertex

x = -b/2a [y = ax^2 + bx + c]

x = -(-6)/2(1) = 6/2 = 3

now that we know the x coordinate is 3 we can plug that back into the original equation to find the y coordinate.

y = (3)^2 - 6(3) + 9 = 9 - 18 + 9 = 0

so the vertex is at (3,0)