Difference of squares

Math

Definition

The difference of squares is a factoring pattern where a² - b² factors into (a + b)(a - b). It applies whenever you subtract two perfect squares.

Examples

  • x² - 9 = (x + 3)(x - 3)
  • 25y² - 16 = (5y + 4)(5y - 4)
  • Mentally computing 51 × 49 = 50² - 1² = 2499
Key Fact

a² - b² = (a + b)(a - b)

Related Terms

Factoring trinomials Factoring by grouping Gcf factoring Solving by factoring

Study This Concept

Practice difference of squares with free review games in these units:

Algebra 1 Unit 7: Factoring