SOLUTION: I am now stuck on the factoring by group. 45x^2 + 39x + 6 I wish math came easier to me! I think I have some of it just not to sure 3(15x^2 + 13x + 2) Thank you for any he

Question 148839: I am now stuck on the factoring by group.
45x^2 + 39x + 6
I wish math came easier to me! I think I have some of it just not to sure
3(15x^2 + 13x + 2)
Thank you for any help!
Answer by Alan3354(69443) (Show Source): You can put this solution on YOUR website!
I am trying to figure out factoring of trinomials. I am sort of lost.
4s^2 - 21s + 5
-----------------
It's a trial an error sometimes. IF it's factorable (it's not always), it'll look like
(js + a)*(ks + b)
a and b can be positive or negative.
Most of the problems in school use integers, not fractions, so try those first.
In this case, the 5 has factors of only 5 and 1, so that narrows it down a lot.
And, it's a +5, so a and b have to have the same sign.
Also, note that the middle term is -21, MINUS, so a and b have to be negative.
-----
So, there are 6 possibilities:
(1s-1)*(4s-5)
(2s-1)*(2s-5)
(4s-1)*(1s-5)
The last one works.
(4s-1)*(s-5) does equal 4s^2 - 21s + 5
There's another way to do this, by solving the quadratic equation but if you haven't seen that yet it might give you a headache.

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