Which of the following expressions is a perfect-square trinomial for every a and b?
Answer and explanation
Correct answer: \(4a^2+12ab+9b^2\)
Here \(4a^2=(2a)^2\) and \(9b^2=(3b)^2\). The required middle term is \(2\times2a\times3b=12ab\), so the expression is \((2a+3b)^2\). Exam tip: always check both the sign and coefficient of the middle term.
Frequently asked questions
What is the correct answer to this question?
\(4a^2+12ab+9b^2\)
Why is this the correct answer?
Here \(4a^2=(2a)^2\) and \(9b^2=(3b)^2\). The required middle term is \(2\times2a\times3b=12ab\), so the expression is \((2a+3b)^2\). Exam tip: always check both the sign and coefficient of the middle term.
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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