If (a_n=40-5n), which will be the first negative term?
Answer and explanation
Correct answer: 9th term
For a negative term, \(40-5n<0\). This gives \(n>8\), so the smallest integer value is \(n=9\). Checking nearby terms, \(a_8=0\), which is not negative, whereas \(a_9=40-45=-5\). Hence, the 9th term is the first negative term. Exam tip: for the “first” term, choose the smallest positive integer satisfying the inequality.
Frequently asked questions
What is the correct answer to this question?
9th term
Why is this the correct answer?
For a negative term, \(40-5n<0\). This gives \(n>8\), so the smallest integer value is \(n=9\). Checking nearby terms, \(a_8=0\), which is not negative, whereas \(a_9=40-45=-5\). Hence, the 9th term is the first negative term. Exam tip: for the “first” term, choose the smallest positive integer satisfying the inequality.
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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