If (a_n=12-2n), which will be the first negative term?
Answer and explanation
Correct answer: 7th term
Given \(a_n=12-2n\), for the first negative term we need \(12-2n<0\). This gives \(n>6\), so the smallest integer value of \(n\) is \(7\). Indeed, \(a_6=0\), which is not negative, whereas \(a_7=12-14=-2\). Therefore, the 7th term is the first negative term. Exam tip: a negative term must be less than \(0\); zero is neither positive nor negative.
Frequently asked questions
What is the correct answer to this question?
7th term
Why is this the correct answer?
Given \(a_n=12-2n\), for the first negative term we need \(12-2n<0\). This gives \(n>6\), so the smallest integer value of \(n\) is \(7\). Indeed, \(a_6=0\), which is not negative, whereas \(a_7=12-14=-2\). Therefore, the 7th term is the first negative term. Exam tip: a negative term must be less than \(0\); zero is neither positive nor negative.
Which subject and chapter does this question cover?
This is a Class 9 Mathematics question. Chapter: Sequences and Progressions. Topic: Explicit or general rule.
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