What is the vertex form of y= (x+2)(x - 7) ?

1 Answer
Jun 14, 2017

minimum vertex -81/4 at (5/2, -81/4)

Explanation:

y = (x + 2)(x - 7) = x^2 - 5 x - 14

use completing a square to solve
y = x^2 - 5 x - 14

y = (x -5/2)^2 -(-5/2)^2 - 14

y = (x -5/2)^2 - 25/4 - 56/4

y = (x -5/2)^2 -81/4

since (x -5/2)^2 is +ve value, therefore it has a minimum vertex -81/4 at (5/2, -81/4)