Question

What is the vertex form of `y=(x + 7)(x + 3)`?

Answer 1

The vertex form is `y=(x+5)^2-4`

Explanation:

`y=(x+7)(x+3)=x^2+10x+21=x^2+10x+25-4`
`y=(x+5)^2-4`
The vertex is at `x=-5` which is also a line of symmetry
and the vertex is at `(-5,-4)`

graph{x^2+10x+21 [-10, 10, -5, 5]}