Question

Factor the trinomial by grouping.
4x^2 + 21x + 27

Answer 1

(4x^2+12x)(9x+27)

Answer 2

i dont see how ya got that

Answer 3

Just a sec, I will get the steps

Answer 4

ok cool. i've tried at least 5 different variations of (4x+_)(x+_) and so on. can't figure anything out

Answer 5

Well, you only need to find ONE, and there is a systematic way to find it WITHOUT guessing

Answer 6

4x^2+21x+27
4x^2+12x + 9x + 27
4x(x+3)+9(x+3)
(x+3)(4x+9)

Answer 7

This is called factoring by grouping. You do not need to guess at any point when factoring by grouping. you find the correct factors the very first time.

Answer 8

so you look at the middle term, usually the one with only an x and you break it down?

Answer 9

if this is true my only question is how do you know how far to break it down by.

Answer 10

Yes, but you have to find the correct numbers to break it down to

Answer 11

you only split the middle term into two numbers that will allow you to factor by grouping. When you factor by grouping you need four terms because you will factor what's common to the first two terms, then factor what's common to the last two terms.

Answer 12

ok i understand. thanks for the explanation!