Which of the following trinomials is the expansion of the square of a binomial?
Answer and explanation
Correct answer: \(4x^2-12xy+9y^2\)
\(4x^2-12xy+9y^2=(2x)^2-2(2x)(3y)+(3y)^2=(2x-3y)^2\), so A is a perfect square. In B, the middle term should be \(-12xy\), not \(-10xy\). Exam tip: check the middle term using twice the product of square roots.
Frequently asked questions
What is the correct answer to this question?
\(4x^2-12xy+9y^2\)
Why is this the correct answer?
\(4x^2-12xy+9y^2=(2x)^2-2(2x)(3y)+(3y)^2=(2x-3y)^2\), so A is a perfect square. In B, the middle term should be \(-12xy\), not \(-10xy\). Exam tip: check the middle term using twice the product of square roots.
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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