If \(a_n=3\cdot2^{n}+n\) then what is the value of \(a_5\)?
Answer and explanation
Correct answer: 101
Given \(a_n=3\cdot2^n+n\). Substituting \(n=5\), \(a_5=3\cdot2^5+5=3\cdot32+5=96+5=101\). Hence, 101 is the correct option. The value 96 comes from calculating only \(3\cdot2^5\) and incorrectly omitting the final \(+5\). Exam tip: Substitute the term number in every part of the formula before simplifying.
Frequently asked questions
What is the correct answer to this question?
101
Why is this the correct answer?
Given \(a_n=3\cdot2^n+n\). Substituting \(n=5\), \(a_5=3\cdot2^5+5=3\cdot32+5=96+5=101\). Hence, 101 is the correct option. The value 96 comes from calculating only \(3\cdot2^5\) and incorrectly omitting the final \(+5\). Exam tip: Substitute the term number in every part of the formula before simplifying.
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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