If (y=55+3x), what is the difference between (y) at (x=9) and (y) at (x=2)?
Answer and explanation
Correct answer: 21
The relation is linear: \(y=55+3x\). The difference between the two \(x\)-values is \(9-2=7\). Since \(y\) increases by 3 for every increase of 1 in \(x\), the difference in \(y\) is \(3\times7=21\). Option 18 would result from incorrectly taking the difference in \(x\) as 6. Exam tip: for a linear expression \(a+bx\), the difference between two \(y\)-values is \(b\) times the difference between the corresponding \(x\)-values.
Frequently asked questions
What is the correct answer to this question?
21
Why is this the correct answer?
The relation is linear: \(y=55+3x\). The difference between the two \(x\)-values is \(9-2=7\). Since \(y\) increases by 3 for every increase of 1 in \(x\), the difference in \(y\) is \(3\times7=21\). Option 18 would result from incorrectly taking the difference in \(x\) as 6. Exam tip: for a linear expression \(a+bx\), the difference between two \(y\)-values is \(b\) times the difference between the corresponding \(x\)-values.
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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