Which rule has initial value (180) and decrease of (15) per step?
Answer and explanation
Correct answer: \(y=180-15x\)
The initial value is the constant term, so it is 180. A decrease of 15 per step means that the coefficient of \(x\) must be \(-15\). Therefore, the rule is \(y=180-15x\). In option A, the value increases rather than decreases. Exam tip: in a linear rule \(y=a+bx\), a negative \(b\) indicates decrease.
Frequently asked questions
What is the correct answer to this question?
\(y=180-15x\)
Why is this the correct answer?
The initial value is the constant term, so it is 180. A decrease of 15 per step means that the coefficient of \(x\) must be \(-15\). Therefore, the rule is \(y=180-15x\). In option A, the value increases rather than decreases. Exam tip: in a linear rule \(y=a+bx\), a negative \(b\) indicates decrease.
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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