Question

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

Answer 1

Answer:

(2, -9)

Step-by-step 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

$= x = \frac{ - 4}{2 \times 1}$

$= x = - \frac{ - 4}{2}$

$= x - ( - 2)$

$= x = 2$

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

= f(2) = -9

= (2, -9)