If (a_n=18-4n), which term is equal to (-30)?
Answer and explanation
Correct answer: 12th term
Given \(a_n=18-4n\), set the nth term equal to \(-30\): \(18-4n=-30\). Thus, \(-4n=-48\), so \(n=12\). Checking, \(a_{12}=18-4(12)=18-48=-30\). Hence, the 12th term is correct. The 13th term gives \(-34\), not \(-30\). Exam tip: handle signs carefully when solving equations involving negative numbers.
Frequently asked questions
What is the correct answer to this question?
12th term
Why is this the correct answer?
Given \(a_n=18-4n\), set the nth term equal to \(-30\): \(18-4n=-30\). Thus, \(-4n=-48\), so \(n=12\). Checking, \(a_{12}=18-4(12)=18-48=-30\). Hence, the 12th term is correct. The 13th term gives \(-34\), not \(-30\). Exam tip: handle signs carefully when solving equations involving negative numbers.
Which subject and chapter does this question cover?
This is a Class 9 Mathematics question. Chapter: Sequences and Progressions. Topic: nth term.
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