What is obtained after simplifying (7(2r-3)+4(r+1))?
Answer and explanation
Correct answer: \(18r-17\)
Use the distributive property: \(7(2r-3)=14r-21\) and \(4(r+1)=4r+4\). Thus, \(14r-21+4r+4=18r-17\). Therefore, the correct expression is \(18r-17\). The option \(18r+25\) may result from incorrectly adding the constant terms with their signs. Exam tip: while expanding brackets, multiply the outside number by every term inside the bracket.
Frequently asked questions
What is the correct answer to this question?
\(18r-17\)
Why is this the correct answer?
Use the distributive property: \(7(2r-3)=14r-21\) and \(4(r+1)=4r+4\). Thus, \(14r-21+4r+4=18r-17\). Therefore, the correct expression is \(18r-17\). The option \(18r+25\) may result from incorrectly adding the constant terms with their signs. Exam tip: while expanding brackets, multiply the outside number by every term inside the bracket.
Which subject and chapter does this question cover?
This is a Class 9 Mathematics question. Chapter: Introduction to Polynomials. Topic: Algebraic expressions.
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