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  • Grade 9
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Common factor of three terms worksheets

Three terms, one shared factor: 6x² + 9x + 12 all divide by 3. These free printable worksheets take the greatest common factor out of a three-term expression.

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Ready to printCommon factor of three terms
Common factor of three terms worksheet — Three terms, free printable with answer key

The answer key prints on a separate page.

What's on this sheet

With three terms the common factor still comes out in front, but now every term has to be checked, and the one that gets forgotten is the last one. In 6x² + 9x + 12 a child divides the 6 and the 9, reaches the 12, and either drops it or divides it wrong — so the walks divide all three, out loud, one at a time.

Why this sheet works

GREATEST is still the whole difficulty. All three of 6, 9 and 12 share 3, and that is the biggest number that divides every one — 6 divides the first and last but not the 9, so it is not available. Listing the divisors of each coefficient and taking the largest they all share is what turns this from a guess into a method.

How this one works

One question from this sheet, worked through a step at a time.

102x² + 187x + 51

102x² + 187x + 51
10218751
102:1236173451102
187:11117187
51:131751
17 × (6x² + 11x + 3)
102x² + 187x + 51=17(6x² + 11x + 3)
  1. Before anything else, look at whether every term shares a factor. The numbers here are 102, 187, 51 — so the question is what the biggest number that divides ALL of them is.
  2. List what divides each one and look for the biggest they all share. 102: 1, 2, 3, 6, 17, 34, 51, 102 187: 1, 11, 17, 187 51: 1, 3, 17, 51.
  3. The biggest number in all of those lists is 17. Take it out in front and divide every term by it: 102 ÷ 17 = 6, 187 ÷ 17 = 11, 51 ÷ 17 = 3.
  4. Check the bracket before you stop. 6x² + 11x + 3 — those numbers share nothing but 1, so there is no more to take out and 17 really was the greatest. 102x² + 187x + 51 = 17(6x² + 11x + 3).