Common Factors Look for something that you can divide all the terms by. You want the biggest possible factor you can divide them all by. The remaining terms, after dividing by the common factor, are left in a bracket. Example #1: 3x2 + 21x + 36 Take out the common factor: = 3(x2 + 7x + 12) Example #2: 4x2y + 16xy - 84y Take out the common factor: = 4y(x2 + 4x - 21) Example #3: 50x2 - 8 Take out the common factor: = 2(25x2 - 4) You should have the times tables up to 12 x 12 memorized by now. If not, make that a priority. Many of these questions will be unnecessarily difficult if you don't have the times tables memorized. Return to 'Explanations' Page | Back to Flow Chart