Riya expanded \((2x+1)^2\) as \(4x^2+1\). Which term is missing from her expansion?
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Answer and explanation
Correct answer: \(4x\)
Using \((a+b)^2=a^2+2ab+b^2\), put \(a=2x\) and \(b=1\). The middle term is \(2\times2x\times1=4x\). \(2x\) misses the factor 2 in 2ab. Exam tip: calculate the middle term separately.
Frequently asked questions
What is the correct answer to this question?
\(4x\)
Why is this the correct answer?
Using \((a+b)^2=a^2+2ab+b^2\), put \(a=2x\) and \(b=1\). The middle term is \(2\times2x\times1=4x\). \(2x\) misses the factor 2 in 2ab. Exam tip: calculate the middle term separately.
Which subject and chapter does this question cover?
This is a Class 9 Mathematics question. Chapter: Exploring Algebraic Identities. Topic: Quadratic expressions.
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