What is obtained after simplifying (3(a-b)+2(2a+b))?
Answer and explanation
Correct answer: \(7a-b\)
On expanding the brackets, \(3(a-b)+2(2a+b)=3a-3b+4a+2b\). Combining like terms gives \(3a+4a=7a\) and \(-3b+2b=-b\). Therefore, the simplified expression is \(7a-b\). The option \(7a+b\) results from combining the terms containing \(b\) incorrectly. Exam tip: multiply the number outside a bracket by every term inside it.
Frequently asked questions
What is the correct answer to this question?
\(7a-b\)
Why is this the correct answer?
On expanding the brackets, \(3(a-b)+2(2a+b)=3a-3b+4a+2b\). Combining like terms gives \(3a+4a=7a\) and \(-3b+2b=-b\). Therefore, the simplified expression is \(7a-b\). The option \(7a+b\) results from combining the terms containing \(b\) incorrectly. Exam tip: multiply the number outside a bracket by every term inside it.
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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