If (a=2) and (b=-1), what is the value of (3a-2b)?
Answer and explanation
Correct answer: 8
Substituting the given values, \(3a-2b=3(2)-2(-1)=6+2=8\). Since \(b=-1\), \(2b=-2\), so subtracting \(2b\) means subtracting \(-2\), which gives \(+2\). Option 6 is only the value of \(3a\); it ignores the \(-2b\) term. Exam tip: When subtracting a negative number, use brackets first to avoid sign errors.
Frequently asked questions
What is the correct answer to this question?
8
Why is this the correct answer?
Substituting the given values, \(3a-2b=3(2)-2(-1)=6+2=8\). Since \(b=-1\), \(2b=-2\), so subtracting \(2b\) means subtracting \(-2\), which gives \(+2\). Option 6 is only the value of \(3a\); it ignores the \(-2b\) term. Exam tip: When subtracting a negative number, use brackets first to avoid sign errors.
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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