If (a_n=n^3+3n^2-2), what is the value of (a_4)?
Answer and explanation
Correct answer: 110
Substitute n=4: \(a_4=4^3+3(4^2)-2=64+48-2=110\). Therefore, 110 is the correct option. A nearby distractor such as 108 results from an incorrect final calculation; \(3\times4^2\) must be evaluated as 48. Exam tip: calculate powers first, then perform multiplication and addition or subtraction.
Frequently asked questions
What is the correct answer to this question?
110
Why is this the correct answer?
Substitute n=4: \(a_4=4^3+3(4^2)-2=64+48-2=110\). Therefore, 110 is the correct option. A nearby distractor such as 108 results from an incorrect final calculation; \(3\times4^2\) must be evaluated as 48. Exam tip: calculate powers first, then perform multiplication and addition or subtraction.
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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