Which extra term is present in ( (m-n)^2 ) compared with (m^2+n^2)?
Answer and explanation
Correct answer: -2mn
Using the identity \((m-n)^2=m^2-2mn+n^2\), the extra term compared with \(m^2+n^2\) is \(-2mn\). The term \(2mn\) occurs in \((m+n)^2\), so it is a close but incorrect distractor. Exam tip: the middle term in a binomial square is always \(\pm2mn\); use the negative sign for subtraction.
Frequently asked questions
What is the correct answer to this question?
-2mn
Why is this the correct answer?
Using the identity \((m-n)^2=m^2-2mn+n^2\), the extra term compared with \(m^2+n^2\) is \(-2mn\). The term \(2mn\) occurs in \((m+n)^2\), so it is a close but incorrect distractor. Exam tip: the middle term in a binomial square is always \(\pm2mn\); use the negative sign for subtraction.
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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