SOLUTION: Please Factor: 24j^2 - 14j - 3

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Question 372004: Please Factor:
24j^2 - 14j - 3

Found 2 solutions by Fombitz, jsmallt9:
Answer by Fombitz(32388)   (Show Source): You can put this solution on YOUR website!


Answer by jsmallt9(3758)   (Show Source): You can put this solution on YOUR website!

This is a trinomial which does not fit any of the factoring patterns. This means we will have to try various combinations of the factors of 24, the leading coefficient, and 3, the constant term. Since 24 has quite a few pairs of factors this could take some time.

When it look like a trinomial might take a lot of trial and error, you might want to consider the following:
So

which is the same answer we would get if we had taken the time to find the one and only combination of factors of 24 and 3.

P.S. In response to your question in your "Thank you"...
You are correct in thinking that patterns will not work on your expression. But patterns are not the only way to factor your expression.

As I tried to explain above, using the Quadratic Formula is an alternative way to factor. (It isn't often taught but I thought you might like to see it.) If you haven't learned the Quadratic Formula then clearly should should not try to use it in this way.

Instead there is yet another way, as I mentioned above, to factor your expression. And that is to find the right combination of factors of 24 and 3. You just try different combinations, in a trial and error way, until you find the one combination which, when multiplied together, actually works out to be . For example:
(24j + 1)(j - 3) which works out to be
(24j - 1)(j + 3) which works out to be
(24j + 3)(j - 1) which works out to be
(24j - 3)(j + 1) which works out to be
(12j + 1)(2j - 3) which works out to be
(12j - 1)(2j + 3) which works out to be
(12j + 3)(2j - 1) which works out to be
(12j - 3)(2j + 1) which works out to be
None of these work out to be . If you methodically go through all the different combinations, you will, sooner or later, end up trying:
(4j-3)(6j+1) which works out to be
This is the only combination that will work!

As you can see, this trial and error technique for factoring trinomials, especially when there a lot of possible combinations, can take a long time. That is why I showed you the Quadratic Formula. The formula is not the easiest to work with but some like using it in a situation like this because it is a fairly direct way to find out