Then the common factors are those that are found in both lists: It is simply the largest of the common factors. In our previous example, the largest of the common factors is 15, so the Greatest Common Factor of 15, 30 and 105 is 15 The "Greatest Common Factor" is the largest of the common factors ...
Create smaller groups within the problem, usually done by grouping the first two terms together and the last two terms together. Step 3: Factor out the GCF from each of the two groups. In the second group, you have a choice of factoring out a positive or negative number.
Write down all factor pairs of 4 (Note: since 5 is positive we only need to think about pairs that are either both positive or both negative. Remember a negative times a negative is a positive. As the chart on the right shows you -2*-2 is positive 4...so we do have to consider these two negative factors.
Formula For Factoring Trinomials (when a =1) It's always easier to understand a new concept by looking at a specific example so you might want to do that first. This formula works when 'a' is 1. In other words, we will use this approach whenever the coefficient in from of x 2 is 1. (If you need help factoring trinomials when $$a \ne 1 $$, then go here.