Which of the following nth-term formulas represents an AP with common difference \(-\frac{5}{2}\)?
Advertisement
Answer and explanation
Correct answer: \(a_n=\frac{19-5n}{2}\)
For an AP written as \(a_n=A+Bn\), the difference \(a_{n+1}-a_n=B\). In option A, the coefficient of \(n\) is \(-\frac{5}{2}\). Option B has a positive difference, while C has difference \(-5\). Exam tip: inspect the coefficient of \(n\).
Frequently asked questions
What is the correct answer to this question?
\(a_n=\frac{19-5n}{2}\)
Why is this the correct answer?
For an AP written as \(a_n=A+Bn\), the difference \(a_{n+1}-a_n=B\). In option A, the coefficient of \(n\) is \(-\frac{5}{2}\). Option B has a positive difference, while C has difference \(-5\). Exam tip: inspect the coefficient of \(n\).
Which subject and chapter does this question cover?
This is a Class 10 Mathematics question. Chapter: Arithmetic Progressions (AP). Topic: Finding the $n$th term of an AP.
Advertisement