If (C(x)=100-5x) and (D(x)=80-x), when will both be equal?
Answer and explanation
Correct answer: \(x=5\)
For the two expressions to be equal, set \(C(x)=D(x)\): \(100-5x=80-x\). This gives \(20=4x\), so \(x=5\). Therefore, option B is correct. Substituting \(x=4\) does not give equal values, so that close distractor is incorrect. Exam tip: To find where two linear expressions are equal, equate them first and then solve for \(x\).
Frequently asked questions
What is the correct answer to this question?
\(x=5\)
Why is this the correct answer?
For the two expressions to be equal, set \(C(x)=D(x)\): \(100-5x=80-x\). This gives \(20=4x\), so \(x=5\). Therefore, option B is correct. Substituting \(x=4\) does not give equal values, so that close distractor is incorrect. Exam tip: To find where two linear expressions are equal, equate them first and then solve for \(x\).
Which subject and chapter does this question cover?
This is a Class 9 Mathematics question. Chapter: Introduction to Polynomials. Topic: Linear growth and decay.
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