If (a=5) and (d=-1), what is the (30)th term?
Answer and explanation
Correct answer: \(-24\)
The \(n\)th term of an AP is \(a_n=a+(n-1)d\). Thus, \(a_{30}=5+(30-1)(-1)=5-29=-24\). Therefore, \(-24\) is correct. The value \(-25\) results from incorrectly using \(30d\) instead of \(29d\). Exam tip: always use \((n-1)d\) in the formula for the \(n\)th term.
Frequently asked questions
What is the correct answer to this question?
\(-24\)
Why is this the correct answer?
The \(n\)th term of an AP is \(a_n=a+(n-1)d\). Thus, \(a_{30}=5+(30-1)(-1)=5-29=-24\). Therefore, \(-24\) is correct. The value \(-25\) results from incorrectly using \(30d\) instead of \(29d\). Exam tip: always use \((n-1)d\) in the formula for the \(n\)th term.
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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