Factoring (x+y)^3 - (x-y)^3
The expression (x+y)^3 - (x-y)^3 can be factored using the difference of cubes formula. This formula states that:
a³ - b³ = (a - b)(a² + ab + b²)
To apply this to our expression, we let:
- a = (x+y)
- b = (x-y)
Substituting these into the difference of cubes formula, we get:
(x+y)³ - (x-y)³ = [(x+y) - (x-y)][(x+y)² + (x+y)(x-y) + (x-y)²]
Now, we simplify each part:
- [(x+y) - (x-y)] = 2y
- [(x+y)² + (x+y)(x-y) + (x-y)²] = (x² + 2xy + y²) + (x² - y²) + (x² - 2xy + y²) = 3x² + y²
Therefore, the factored form of (x+y)³ - (x-y)³ is:
(x+y)³ - (x-y)³ = 2y(3x² + y²)
Key Points:
- The difference of cubes formula is a powerful tool for factoring expressions of this type.
- Recognizing the pattern of cubes allows you to apply the formula efficiently.
- Simplifying the expression after applying the formula is crucial to obtain the final factored form.