Which term contains (yz) in ( (x+2y+5z)^2 )?
Answer and explanation
Correct answer: \(20yz\)
Using \((a+b+c)^2=a^2+b^2+c^2+2ab+2bc+2ca\), the term containing \(yz\) comes from \(2(2y)(5z)\). Thus, \(2\times2\times5\,yz=20yz\), so \(20yz\) is correct. \(10yz\) results from forgetting the factor \(2\) in the cross-product term. Exam tip: while squaring three terms, multiply every product of two unlike terms by \(2\).
Frequently asked questions
What is the correct answer to this question?
\(20yz\)
Why is this the correct answer?
Using \((a+b+c)^2=a^2+b^2+c^2+2ab+2bc+2ca\), the term containing \(yz\) comes from \(2(2y)(5z)\). Thus, \(2\times2\times5\,yz=20yz\), so \(20yz\) is correct. \(10yz\) results from forgetting the factor \(2\) in the cross-product term. Exam tip: while squaring three terms, multiply every product of two unlike terms by \(2\).
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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