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Which of the following expressions can be factorised using the identity for the difference of two squares, \((a^2-b^2)\)?
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Answer and explanation
Correct answer: \(4x^2-25\)
\(4x^2-25=(2x)^2-5^2\), so it is a difference of squares and factorises as \((2x-5)(2x+5)\). Option C is a perfect-square trinomial, not a difference. Exam tip: check for two squared terms separated by subtraction.
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What is the correct answer to this question?
\(4x^2-25\)
Why is this the correct answer?
\(4x^2-25=(2x)^2-5^2\), so it is a difference of squares and factorises as \((2x-5)(2x+5)\). Option C is a perfect-square trinomial, not a difference. Exam tip: check for two squared terms separated by subtraction.
Which subject and chapter does this question cover?
This is a Class 9 Mathematics question. Chapter: Exploring Algebraic Identities. Topic: Factorisation.
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