Recognize that the expression is a product of three factors: \( (3y - 5)(3y + 5)(9y^2 - 25) \). Notice that the first two factors form a difference of squares pattern.
Apply the difference of squares formula to the first two factors: \( (a - b)(a + b) = a^2 - b^2 \). Here, \(a = 3y\) and \(b = 5\), so \( (3y - 5)(3y + 5) = (3y)^2 - 5^2 = 9y^2 - 25 \).
Substitute the result back into the expression, so now you have \( (9y^2 - 25)(9y^2 - 25) \), which is the square of \( (9y^2 - 25) \).
Rewrite the expression as \( (9y^2 - 25)^2 \) and recognize this as a perfect square binomial.
Expand \( (9y^2 - 25)^2 \) using the formula \( (A - B)^2 = A^2 - 2AB + B^2 \), where \( A = 9y^2 \) and \( B = 25 \). Write out the expanded form without simplifying the coefficients.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Polynomial Multiplication
Polynomial multiplication involves multiplying each term in one polynomial by every term in the other polynomial(s) and then combining like terms. This process extends the distributive property and is essential for expanding expressions like (3y - 5)(3y + 5).
The difference of squares is a special product formula: (a - b)(a + b) = a² - b². Recognizing this pattern simplifies multiplication, as seen in (3y - 5)(3y + 5), which equals 9y² - 25, reducing the complexity of the problem.
Solving Quadratic Equations by Completing the Square
Combining Like Terms
After multiplying polynomials, combining like terms means adding or subtracting terms with the same variable and exponent. This step simplifies the expression into its standard form, making it easier to interpret or use in further calculations.