If (a_n=5n-1), what is the (20)th term of this AP?
Answer and explanation
Correct answer: 99
The general term is \(a_n=5n-1\). To find the 20th term, substitute \(n=20\): \(a_{20}=5(20)-1=100-1=99\). Therefore, 99 is correct. The value 101 would result from adding 1 instead of subtracting it. Exam tip: In an \(n\)th-term question, first substitute the required term number for \(n\).
Frequently asked questions
What is the correct answer to this question?
99
Why is this the correct answer?
The general term is \(a_n=5n-1\). To find the 20th term, substitute \(n=20\): \(a_{20}=5(20)-1=100-1=99\). Therefore, 99 is correct. The value 101 would result from adding 1 instead of subtracting it. Exam tip: In an \(n\)th-term question, first substitute the required term number for \(n\).
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.
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