If (y=20+kx) and (y=35) at (x=3), what is (k)?
Answer and explanation
Correct answer: 5
At \(x=3\), the value of \(y\) is 35. Substituting these values in \(y=20+kx\) gives \(35=20+3k\). Hence, \(3k=15\), so \(k=5\). Option 15 is the value of \(3k\), not of \(k\). Exam tip: In a linear expression, substitute the given values of \(x\) and \(y\) first, then isolate the unknown coefficient.
Frequently asked questions
What is the correct answer to this question?
5
Why is this the correct answer?
At \(x=3\), the value of \(y\) is 35. Substituting these values in \(y=20+kx\) gives \(35=20+3k\). Hence, \(3k=15\), so \(k=5\). Option 15 is the value of \(3k\), not of \(k\). Exam tip: In a linear expression, substitute the given values of \(x\) and \(y\) first, then isolate the unknown coefficient.
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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