Question

What is the the vertex of `y = (x -3)^2+8x-15`?

Answer 1

The vertex is `(-1,-7)`.

Explanation:

First expand and collect like terms:

`y=x^2-6x+9+8x-15`
`y=x^2 + 2x -6`

Now the vertex is `(h,k)`, where `h=-b/(2a)` and `k` is the value of `y` when `h` is substituted into the function.

`h=-2/(2*1)=-1`

`k = (-1)^2 +2(-1) -6 = 1-2-6=-7`

The vertex is `(-1,-7)`.