If (a=1) and (d=11), what is the (9)th term?
Answer and explanation
Correct answer: 89
The nth term of an arithmetic progression is \(a_n=a+(n-1)d\). Thus, \(a_9=1+(9-1)\times11=1+88=89\). Therefore, 89 is correct. A common error is choosing 88 by forgetting to include the first term; only 8 common differences are added to reach the 9th term. Exam tip: always use \((n-1)\), not \(n\), in the nth-term formula.
Frequently asked questions
What is the correct answer to this question?
89
Why is this the correct answer?
The nth term of an arithmetic progression is \(a_n=a+(n-1)d\). Thus, \(a_9=1+(9-1)\times11=1+88=89\). Therefore, 89 is correct. A common error is choosing 88 by forgetting to include the first term; only 8 common differences are added to reach the 9th term. Exam tip: always use \((n-1)\), not \(n\), in the nth-term formula.
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.
Student feedback
Was this question useful?
👍 0 Helpful 👎 0 Not helpful
Yes 0% No 0%
0 responsesStudent Reviews
No published reviews yet.
