If (p(x)=3x-2) and (q(x)=5x+4), what is (2q(x)-p(x))?
Answer and explanation
Correct answer: \(7x+10\)
First multiply \(q(x)\) by 2: \(2q(x)=2(5x+4)=10x+8\). Now subtract \(p(x)\): \(10x+8-(3x-2)=10x+8-3x+2=7x+10\). Hence, \(7x+10\) is correct. \(7x+6\) results from mishandling the sign of \(-2\) while subtracting \((3x-2)\). Exam tip: when a minus sign appears before a polynomial, change the signs of all terms inside the bracket.
Frequently asked questions
What is the correct answer to this question?
\(7x+10\)
Why is this the correct answer?
First multiply \(q(x)\) by 2: \(2q(x)=2(5x+4)=10x+8\). Now subtract \(p(x)\): \(10x+8-(3x-2)=10x+8-3x+2=7x+10\). Hence, \(7x+10\) is correct. \(7x+6\) results from mishandling the sign of \(-2\) while subtracting \((3x-2)\). Exam tip: when a minus sign appears before a polynomial, change the signs of all terms inside the bracket.
Which subject and chapter does this question cover?
This is a Class 9 Mathematics question. Chapter: Introduction to Polynomials. Topic: Linear polynomials.
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