Question

Completely factor 12x² - 7x - 12.

A.
(4x + 3)(3x - 4)



B.
(12x + 1)(x - 12)



C.
(12x - 12)(x + 1)



D.
(4x - 4)(3x + 3)

Answer 1

You can solve this a few ways. You could use the quadratic formula but I am going to use the grouping method.


`12x^2 - 7x - 12`
First find two numbers that equal -12 when you multiply them but also equals -7 when you add them. Two numbers that do just that are -16 and 9

Now use the two numbers and put it in group form

`12x^2 - 7x - 12`

`12x^2 - 16x + 9x - 12`

`(12x^2 - 16x) + (9x - 12)`

Now factor out the groups

`(12x^2 - 16x) + (9x - 12)`

`4x(3x - 4) + 3(3x - 4)`

`(4x + 3)(3x - 4)`
The answer is A