Factor completely: 3a2 + 5a − 12

Prime

(3a + 4)(a − 3)

(3a − 4)(a + 3)

(3a − 3)(a + 4)

Question

Factor completely: 3a2 + 5a − 12 

Prime 

(3a + 4)(a − 3) 

(3a − 4)(a + 3) 

(3a − 3)(a + 4)

johnweldon1993 · Answer

okay....now that openstudy is done updating...

what are the factors of 12?
12 and 1
6 and 2
4 and 3

which of those combinations add up to 5? none right? well look we have a coefficient in front of a² ...so...what are the factors of 3?
3 and 1 right?

so

(3a   )(a    )
something like this

now lets plug in some terms to check

(3a + 4) (a - 3)
3a² - 9a + 4a - 12...thats not it because -9a and 4a add to -5...we need +5

(3a - 4)(a + 3)
3a² + 9a - 4a - 12 ...look there...9a - 4a...is 5a so we have

3a² + 5a - 12

theres out answer :)

anonymous · Answer

whats the answer though?