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If (a_n=5^n-2n), what is the value of (a_3)?
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Answer and explanation
Correct answer: 119
Given \(a_n=5^n-2n\). Substituting \(n=3\), \(a_3=5^3-2(3)=125-6=119\). Therefore, 119 is correct. The value 121 may result from incorrectly subtracting 4 instead of \(2n=6\). Exam tip: substitute the required term number for \(n\) in every part of the rule.
Frequently asked questions
What is the correct answer to this question?
119
Why is this the correct answer?
Given \(a_n=5^n-2n\). Substituting \(n=3\), \(a_3=5^3-2(3)=125-6=119\). Therefore, 119 is correct. The value 121 may result from incorrectly subtracting 4 instead of \(2n=6\). Exam tip: substitute the required term number for \(n\) in every part of the rule.
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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