Which of the following expressions is a perfect-square trinomial and can be written as the square of a binomial?
Answer and explanation
Correct answer: \(4a^2-12ab+9b^2\)
\(4a^2-12ab+9b^2=(2a-3b)^2\). Its middle term is \(-2\times2a\times3b=-12ab\). Option D has \(-6ab\), so it is not a perfect square. Exam tip: compare the middle term with twice the product of the square roots of the outer terms.
Frequently asked questions
What is the correct answer to this question?
\(4a^2-12ab+9b^2\)
Why is this the correct answer?
\(4a^2-12ab+9b^2=(2a-3b)^2\). Its middle term is \(-2\times2a\times3b=-12ab\). Option D has \(-6ab\), so it is not a perfect square. Exam tip: compare the middle term with twice the product of the square roots of the outer terms.
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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