SOLUTION: Could someone help me please with this problem? I am having a meltdown with trinomials and factoring. I am supposed to factor each trinomial using trial and error, I am STUCK!:

Algebra ->  Polynomials-and-rational-expressions -> SOLUTION: Could someone help me please with this problem? I am having a meltdown with trinomials and factoring. I am supposed to factor each trinomial using trial and error, I am STUCK!:      Log On


   

Question 16814: Could someone help me please with this problem?
I am having a meltdown with trinomials and factoring.
I am supposed to factor each trinomial using trial and error, I am STUCK!:
15x^2-x-2 and 15x^2 + 13x-2
Thank you in advance and all help is appreciated!
Angela
Answer by Earlsdon(6294) About Me  (Show Source):
You can put this solution on YOUR website!
1) Factor:
15x%5E2+-+x+-+2
What are the factors of 15x^2?
%2815x%29%28x%29+=+15x%5E2
%285x%29%283x%29+=+15x%5E2
%28-15x%29%28-x%29+=+15x%5E2
%28-5x%29%28-3x%29+=+15x%5E2
What are the factors of -2?
%28-1%29%282%29+=+-2
%281%29%28-2%29+=+-2
Now you can use trial & error. Pick a pair of factors from the first list and a pair of factors from the second list.
But keep in mind that you want the right combination that will make a (-x) for the middle term of your trinomial.
Try: %285x+-+1%29%283x+%2B+2%29+=+15x%5E2+%2B+10x+-+3x+-+2 = 15x%5E2+%2B+7x+-+2 Oops!
Almost...but no cigar! Try switching the -1 and the 2
%285x+%2B+2%29%283x+-+1%29+=+15x%5E2+-+5x+%2B+6x+-+2 = 15x%5E2+%2B+x+-+2 Not quite!
You need a -x not a +x
Try %285x+-+2%29%283x+%2B+1%29+=+15x%5E2+%2B+5x+-+6x+-+2 = 15x%5E2+-+x+-+2 Bingo!
Now try this approach on your second problem.