Worked examples
Two examples
Example 1
Factor out the greatest common factor: 6x + 9
- The largest number that goes into 6 and 9 is 3.
- Divide each term by 3: 2x and 3. Check: 3(2x + 3) = 6x + 9.
Answer: 3(2x + 3)
Example 2
Factor out the greatest common factor: 10x2 − 15x
- The largest number is 5, and both terms have an x: take out 5x.
- 10x2 ÷ 5x = 2x, and −15x ÷ 5x = −3.
Answer: 5x(2x − 3)
Where this is taught: Quiz 39: Polynomials and Factoring, “Look for a common factor first”
The drill
Ten problems
How many:
Type your answer as the common factor times parentheses, like 3(2x + 5). Then press Check my answers at the bottom.Write each answer on the line. The answer key, with the reasoning, is on the last page.