Which option has (y) decreasing by (5) each time (x) increases and (y(0)=80)?
Answer and explanation
Correct answer: \(y=80-5x\)
In a linear expression, the constant term gives \(y(0)\), so it must be \(80\). Since \(y\) must decrease by 5 when \(x\) increases by 1, the coefficient of \(x\) must be \(-5\). Hence, \(y=80-5x\) is correct. Option A has the correct initial value, but it makes \(y\) increase by 5 instead. Exam tip: check the constant term for \(y(0)\) and the coefficient of \(x\) for the rate of change.
Frequently asked questions
What is the correct answer to this question?
\(y=80-5x\)
Why is this the correct answer?
In a linear expression, the constant term gives \(y(0)\), so it must be \(80\). Since \(y\) must decrease by 5 when \(x\) increases by 1, the coefficient of \(x\) must be \(-5\). Hence, \(y=80-5x\) is correct. Option A has the correct initial value, but it makes \(y\) increase by 5 instead. Exam tip: check the constant term for \(y(0)\) and the coefficient of \(x\) for the rate of change.
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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