Which of the following expressions is always a perfect-square trinomial?
Answer and explanation
Correct answer: \(a^2+2ab+b^2\)
\(a^2+2ab+b^2=(a+b)^2\), so it is always a perfect-square trinomial. Option B has middle term \(ab\), but a square of a binomial requires \(2ab\). Exam tip: check the middle coefficient first.
Frequently asked questions
What is the correct answer to this question?
\(a^2+2ab+b^2\)
Why is this the correct answer?
\(a^2+2ab+b^2=(a+b)^2\), so it is always a perfect-square trinomial. Option B has middle term \(ab\), but a square of a binomial requires \(2ab\). Exam tip: check the middle coefficient first.
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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