If (a_n=15-3n), which will be the first negative term?
Answer and explanation
Correct answer: sixth term
For a term to be negative, \(15-3n<0\). This gives \(n>5\), so the smallest integer value is \(n=6\). In fact, \(a_5=15-3(5)=0\), which is not negative, whereas \(a_6=15-3(6)=-3\). Hence, the sixth term is the first negative term. Exam tip: when asked for the first such term, choose the smallest natural-number index satisfying the inequality.
Frequently asked questions
What is the correct answer to this question?
sixth term
Why is this the correct answer?
For a term to be negative, \(15-3n<0\). This gives \(n>5\), so the smallest integer value is \(n=6\). In fact, \(a_5=15-3(5)=0\), which is not negative, whereas \(a_6=15-3(6)=-3\). Hence, the sixth term is the first negative term. Exam tip: when asked for the first such term, choose the smallest natural-number index satisfying the inequality.
Which subject and chapter does this question cover?
This is a Class 9 Mathematics question. Chapter: Sequences and Progressions. Topic: Explicit or general rule.
Student feedback
Was this question useful?
👍 0 Helpful 👎 0 Not helpful
Yes 0% No 0%
0 responsesStudent Reviews
No published reviews yet.
