Rewrite the equation in vertex form by completing the square

f(x)=(3x-9)(x+1)

f(x) = 3(x - 1)² - 12

Step-by-step explanation:

Given

f(x) = (3x - 9)(x + 1) ← expand factors using FOIL

     = 3x² - 6x - 9

To complete the square the coefficient of the x² term must be 1

Factor 3 out of 3x² - 6x

f(x) = 3(x² - 2x) - 9

To complete the square

add/subtract ( half the coefficient of the x- term )² to x² - 2x

f(x) = 3(x² + 2(- 1)x + 1 - 1) - 9

     = 3(x - 1)² - 3 - 9

     = 3(x - 1)² - 12 ← equation in vertex form

answer: i don't understand it

step-by-step explanation: sorry

what is the question? i am guessing you are looking for the area.

to find an area, you have to do length x width.

in this case, it would be 12 ft x 4 ft = 48 sq. ft