Question

Question #64f21

Answer 1

x- intercept at `-4` and `2`
The coordinate of vertex is minimum at `(-1,-9)`

Explanation:

`y = x^2 + 2 x -8`

we can find `x`-intercept when `y =0` or we can use completing a square to solve both questions straight away.

`y = x^2 + 2 x -8`
`y = (x + 1)^2 - (1)^2 - 8`
`y = (x + 1)^2 - 9`

when `y =0` then,
`x + 1)^2 - 9 = 0`
`(x + 1)^2 - 9 = 0`
`(x + 1)^2 = 9`
`x + 1 = sqrt 9 = +- 3`
`x = -1 +- 3`
`x = -1-3 = -4 and -1+3 = 2->` x- intercept

The coordinate of vertex is minimum at `(-1,-9)`