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If (a_n=n^2+2^n), what will be the value of (a_4+a_5)?
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Answer and explanation
Correct answer: 89
Given \(a_n=n^2+2^n\), \(a_4=4^2+2^4=16+16=32\) and \(a_5=5^2+2^5=25+32=57\). Therefore, \(a_4+a_5=32+57=89\). Option 85 may result from an error in calculating either \(5^2\) or \(2^5\). Exam tip: evaluate the square and exponential parts separately before adding them.
Frequently asked questions
What is the correct answer to this question?
89
Why is this the correct answer?
Given \(a_n=n^2+2^n\), \(a_4=4^2+2^4=16+16=32\) and \(a_5=5^2+2^5=25+32=57\). Therefore, \(a_4+a_5=32+57=89\). Option 85 may result from an error in calculating either \(5^2\) or \(2^5\). Exam tip: evaluate the square and exponential parts separately before adding them.
Which subject and chapter does this question cover?
This is a Class 9 Mathematics question. Chapter: Sequences and Progressions. Topic: Sequences.
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