Question

F(x) = (x + 1)(x - 5). What is the vertex?
(1,5)
(5.1)
(2.-9)
(-9,2)​

Answer 1

(2, -9)

Explanation:

f(x) = (x + 1)(x - 5)

`=f(x) = {x}^(2) - 5x + x - 5`

`= f(x) = {x}^(2) - 4x - 5`

`= f(x) = {1x}^(2) - 4x - 5`

`= f(x) = {1x}^(2) + ( - 4x) - 5`

= a = 1, b = -4

`= x = ( - 4)/(2 * 1)`

`= x = - ( - 4)/(2)`

`= x - ( - 2)`

`= x = 2`

= f(x) = (x + 1) x (x - 5); x = 2

= f(2) = -9

= (2, -9)