(a-b)(a^2+ab+b^2)

2 min read Jun 16, 2024
(a-b)(a^2+ab+b^2)

Understanding the Expansion of (a - b)(a² + ab + b²)

The expression (a - b)(a² + ab + b²) is a classic example of a difference of cubes factorization. This particular pattern appears frequently in algebra and can be expanded using a simple rule.

The Difference of Cubes Formula

The general formula for the difference of cubes is:

a³ - b³ = (a - b)(a² + ab + b²)

This formula shows that the difference of two cubes can be factored into a binomial (a - b) and a trinomial (a² + ab + b²).

Expanding the Expression

To expand (a - b)(a² + ab + b²), we simply apply the distributive property:

  1. Multiply the first term of the binomial (a) by each term in the trinomial:

    • a * a² = a³
    • a * ab = a²b
    • a * b² = ab²
  2. Multiply the second term of the binomial (-b) by each term in the trinomial:

    • -b * a² = -a²b
    • -b * ab = -ab²
    • -b * b² = -b³
  3. Combine the resulting terms:

    • a³ + a²b + ab² - a²b - ab² - b³ = a³ - b³

Conclusion

Therefore, expanding (a - b)(a² + ab + b²) using the difference of cubes formula results in a³ - b³. This pattern is crucial for simplifying expressions and solving equations involving the difference of two cubes. Understanding this factorization will prove invaluable for various mathematical operations and problem-solving situations.

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