Worked examples
Two examples
Example 1
Factor: x2 + 5x + 6
- Two numbers that multiply to 6 and add to 5: 2 and 3.
Answer: (x + 2)(x + 3)
Example 2
Factor: x2 − 2x − 15
- Two numbers that multiply to −15 and add to −2: −5 and 3.
Answer: (x − 5)(x + 3)
Where this is taught: Quiz 39: Polynomials and Factoring, “Factoring: running the multiplication backward”
The drill
Ten problems
How many:
Type your answer as a product, like (x + 2)(x - 3). 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.