Which rule has initial value (140) and decrease of (10) per step?
Answer and explanation
Correct answer: \(y=140-10x\)
A linear rule has the form \(y=a+bx\), where \(a\) is the initial value and \(b\) is the change per step. Here, the initial value is 140 and the value decreases by 10 each step, so the change is \(-10\). Therefore, the rule is \(y=140-10x\). Option A represents an increase of 10 per step. Exam tip: words such as “decrease” or “decay” indicate a negative slope.
Frequently asked questions
What is the correct answer to this question?
\(y=140-10x\)
Why is this the correct answer?
A linear rule has the form \(y=a+bx\), where \(a\) is the initial value and \(b\) is the change per step. Here, the initial value is 140 and the value decreases by 10 each step, so the change is \(-10\). Therefore, the rule is \(y=140-10x\). Option A represents an increase of 10 per step. Exam tip: words such as “decrease” or “decay” indicate a negative slope.
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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