Algebra: Chapter 6, Lesson 6, page 281.
Factoring by Grouping
Factoring by grouping works for polynomials that are greater than trinomials. Grouping usually works with polynomials that have 4 terms. All that you have to do is group the polynomials into binomials using parentheses. But, remember, that not all 4 term expressions can be factored this way.
Example: `6x^3+9x^2+4x+6` becomes `(6x^3+9x^2)+(4x+6)`.
We can factor out a `3x^2` from the first binomial and a `2` from the second binomial leaving us with `(3x^2)(2x+3)+2(2x+3)` or factoring out the `(2x+3)`, we have`(2x+3)(3x^2+2)`.
Here is a link from purplemath.com. She calls it factoring in “pairs”.