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Which of the following expressions is a perfect-square trinomial and can be written in the form \((x+a)^2\)?
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Answer and explanation
Correct answer: \(x^2+10x+25\)
\((x+a)^2=x^2+2ax+a^2\). Taking \(a=5\) gives the middle term \(2\times x\times5=10x\) and constant term \(25\). Hence A is a perfect square; B has 20 instead of 25. Exam tip: use the square root of the constant to check the middle term.
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What is the correct answer to this question?
\(x^2+10x+25\)
Why is this the correct answer?
\((x+a)^2=x^2+2ax+a^2\). Taking \(a=5\) gives the middle term \(2\times x\times5=10x\) and constant term \(25\). Hence A is a perfect square; B has 20 instead of 25. Exam tip: use the square root of the constant to check the middle term.
Which subject and chapter does this question cover?
This is a Class 9 Mathematics question. Chapter: Exploring Algebraic Identities. Topic: Factorisation.
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