CK-12: Andrew Gloag, Anne Gloag, and Melissa Kramer's "Factoring Polynomials Completely"

Scroll down to the section titled "Factoring by Grouping," and work through Example 3. Then, scroll down to the Practice Set and solve problems 11-15, 17, 18, and 23-27. All of these problems are four-term polynomials that can be factored by grouping. Once you have completed the practice problems, check your answers against the answer key.