Expanding (2x-3)(2x+3)
In algebra, expanding expressions often involves applying the distributive property. This property allows us to multiply terms within parentheses by a factor outside. When we encounter expressions like (2x-3)(2x+3), we can use a handy pattern called the "difference of squares" to simplify the expansion.
Understanding the Difference of Squares Pattern
The difference of squares pattern states:
** (a - b)(a + b) = a² - b² **
This pattern arises because when we expand the left side, the middle terms cancel out:
- (a - b)(a + b) = a(a + b) - b(a + b)
- = a² + ab - ba - b²
- = a² - b²
Applying the Pattern to (2x-3)(2x+3)
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Identify 'a' and 'b':
- In this case, a = 2x and b = 3
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Apply the pattern:
- (2x - 3)(2x + 3) = (2x)² - (3)²
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Simplify:
- = 4x² - 9
Therefore, the expanded form of (2x-3)(2x+3) is 4x² - 9.
Using the FOIL Method (Alternative Approach)
While the difference of squares pattern provides a quicker solution, we can also use the FOIL method (First, Outer, Inner, Last) to expand the expression:
- First: 2x * 2x = 4x²
- Outer: 2x * 3 = 6x
- Inner: -3 * 2x = -6x
- Last: -3 * 3 = -9
Combining like terms, we get 4x² + 6x - 6x - 9, which simplifies to 4x² - 9.
As you can see, both methods lead to the same answer. Choosing the most efficient approach depends on your comfort level and the specific problem you are tackling.