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If (a_n=50-4n), which will be the first term less than (10)?
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Answer and explanation
Correct answer: 11th
We need \(a_n<10\). Thus, \(50-4n<10\), so \(-4n<-40\) and hence \(n>10\). Since \(n\) must be an integer, the smallest possible value is \(11\). In fact, \(a_{10}=10\), which is not less than 10, whereas \(a_{11}=6\). Exam tip: use \(<\), not \(\leq\), for “less than.”
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What is the correct answer to this question?
11th
Why is this the correct answer?
We need \(a_n<10\). Thus, \(50-4n<10\), so \(-4n<-40\) and hence \(n>10\). Since \(n\) must be an integer, the smallest possible value is \(11\). In fact, \(a_{10}=10\), which is not less than 10, whereas \(a_{11}=6\). Exam tip: use \(<\), not \(\leq\), for “less than.”
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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