How To: Factor a trinomial by grouping

Factor a trinomial by grouping In order to factor a trinomial by grouping you must have four terms. In order to have four terms, we are going to break the middle term, 15, into two pieces that can work with the first term, 4x2 and the last term, 9. We multiply 4 x 9 which equals 36. Then we have to find the factors of 36. They are 1 x 36, 2 x 18, 3 x 12, 4 x 9, and 6 x 6. 3+12 equal 15, so this is the factor we'll use to replace the 15, middle factor. We will rewrite the problem as 4x2 + 3x+12x +9. Factor by grouping will be x(4x+3) +3(4x+3. Final answer is (4x+3)(x+3)