Which of the following expressions is a perfect-square trinomial formed by squaring a binomial with terms 5x and 3y, with a negative middle term?
Answer and explanation
Correct answer: \(25x^2-30xy+9y^2\)
Using \((A-B)^2=A^2-2AB+B^2\), take \(A=5x\) and \(B=3y\). This gives \(25x^2-30xy+9y^2\). Option C has a positive middle term, so it represents \((A+B)^2\). Exam tip: always check the sign of the middle term.
Frequently asked questions
What is the correct answer to this question?
\(25x^2-30xy+9y^2\)
Why is this the correct answer?
Using \((A-B)^2=A^2-2AB+B^2\), take \(A=5x\) and \(B=3y\). This gives \(25x^2-30xy+9y^2\). Option C has a positive middle term, so it represents \((A+B)^2\). Exam tip: always check the sign 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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