What is the (9)th term of the AP (20,17,14,11,\ldots)?
Answer and explanation
Correct answer: -4
In this AP, the first term is 20 and the common difference is \(d=17-20=-3\). Using \(a_n=a+(n-1)d\), \(a_9=20+(9-1)(-3)=20-24=-4\). The option -1 can result from an incorrect subtraction. Exam tip: always retain the negative sign of the common difference in a decreasing AP.
Frequently asked questions
What is the correct answer to this question?
-4
Why is this the correct answer?
In this AP, the first term is 20 and the common difference is \(d=17-20=-3\). Using \(a_n=a+(n-1)d\), \(a_9=20+(9-1)(-3)=20-24=-4\). The option -1 can result from an incorrect subtraction. Exam tip: always retain the negative sign of the common difference in a decreasing AP.
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.
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