(x-a)(x+a)

4 min read Jun 17, 2024
(x-a)(x+a)

The Difference of Squares: (x - a)(x + a)

The expression (x - a)(x + a) is a fundamental concept in algebra, known as the difference of squares. It represents a special case of factoring that simplifies complex expressions and offers valuable insights into algebraic manipulation.

Understanding the Pattern

The difference of squares pattern arises from the multiplication of two binomials: one with a positive term and the other with a negative term. Let's break down the expansion:

(x - a)(x + a) = x(x + a) - a(x + a)

Expanding further:

= x² + xa - ax - a²

Since "xa" and "ax" are the same, they cancel each other out, leaving us with:

= x² - a²

This illustrates the core concept: the product of two binomials, one with a positive and one with a negative term, always results in the difference of the squares of those terms.

Applications of the Difference of Squares

The difference of squares pattern has numerous applications in algebra and beyond:

  • Factoring expressions: Recognizing the difference of squares pattern allows us to factor expressions quickly and efficiently. For example, x² - 9 can be factored as (x + 3)(x - 3).
  • Simplifying algebraic expressions: By applying the difference of squares, we can simplify complex expressions by eliminating common factors. This is particularly useful in solving equations and inequalities.
  • Solving equations: The difference of squares pattern can help us solve equations by factoring them into simpler expressions. For instance, x² - 16 = 0 can be solved by factoring into (x + 4)(x - 4) = 0, leading to solutions x = 4 and x = -4.
  • Geometric applications: The difference of squares pattern finds applications in geometry, such as calculating the area of squares or the difference in area between two squares.

Examples

Here are some examples to illustrate the application of the difference of squares pattern:

1. Factoring:

  • 4x² - 25 = (2x + 5)(2x - 5)

2. Simplifying expressions:

  • (x² - y²)/(x - y) = (x + y)(x - y)/(x - y) = x + y

3. Solving equations:

  • 9x² - 1 = 0
    • (3x + 1)(3x - 1) = 0
    • x = -1/3, x = 1/3

Conclusion

The difference of squares pattern, (x - a)(x + a) = x² - a², is a powerful tool in algebra. Its ability to factor expressions, simplify complex equations, and solve problems makes it a crucial concept to understand. By recognizing this pattern and its applications, we can simplify mathematical operations and gain deeper insights into algebraic manipulations.

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