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Which of the following statements shows the correct use of the identity for the difference of squares?
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Answer and explanation
Correct answer: \(x^4-81y^4=(x^2-9y^2)(x^2+9y^2)\)
\(x^4-81y^4=(x^2)^2-(9y^2)^2\). Applying \(a^2-b^2=(a-b)(a+b)\) gives option A. Option C has a sum, not a difference. Exam tip: first rewrite both terms as perfect squares.
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What is the correct answer to this question?
\(x^4-81y^4=(x^2-9y^2)(x^2+9y^2)\)
Why is this the correct answer?
\(x^4-81y^4=(x^2)^2-(9y^2)^2\). Applying \(a^2-b^2=(a-b)(a+b)\) gives option A. Option C has a sum, not a difference. Exam tip: first rewrite both terms as perfect squares.
Which subject and chapter does this question cover?
This is a Class 9 Mathematics question. Chapter: Exploring Algebraic Identities. Topic: Algebraic identities.
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