Which option has (y) decreasing by (8) each time (x) increases and (y(0)=130)?
Answer and explanation
Correct answer: \(y=130-8x\)
A linear relation has the form \(y=a+bx\), where \(a=y(0)\) and \(b\) is the change in \(y\) for each increase of 1 in \(x\). Here, \(y(0)=130\) and \(y\) decreases by 8 each time, so \(b=-8\). Hence, \(y=130-8x\). In option A, \(y\) increases, while option B has initial value 8. Exam tip: put \(x=0\) to identify the initial value from the constant term.
Frequently asked questions
What is the correct answer to this question?
\(y=130-8x\)
Why is this the correct answer?
A linear relation has the form \(y=a+bx\), where \(a=y(0)\) and \(b\) is the change in \(y\) for each increase of 1 in \(x\). Here, \(y(0)=130\) and \(y\) decreases by 8 each time, so \(b=-8\). Hence, \(y=130-8x\). In option A, \(y\) increases, while option B has initial value 8. Exam tip: put \(x=0\) to identify the initial value from the constant term.
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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