Question

What is the vertex of `y= 2x^2- 8x -(x-3)^2`?

Answer 1

Vertex (1, -10)

Explanation:

Develop y:
`y = 2x^2 - 8x - (x^2 - 6x + 9)`
`y = 2x^2 - 8x - x^2 + 6x - 9`
`y = x^2 - 2x - 9`
x-coordinate of vertex:
`x = -b/(2a) = - (-2/2) = 1`
y-coordinate of vertex:
`y(1) = 1 - 2 - 9 = - 10`
Vertex (1, -10)
graph{x^2- 2x - 9 [-20, 20, -10, 10]}