If (a_n=(3n-2)^2), what is the value of (a_4)?
Answer and explanation
Correct answer: 100
Given \(a_n=(3n-2)^2\). Substituting \(n=4\), \(a_4=(3\times4-2)^2=(12-2)^2=10^2=100\). Therefore, 100 is the correct option. \(121\) would result only if the expression inside the square were 11, which it is not here. Exam tip: substitute the value of \(n\) first, then simplify the bracket before applying the exponent.
Frequently asked questions
What is the correct answer to this question?
100
Why is this the correct answer?
Given \(a_n=(3n-2)^2\). Substituting \(n=4\), \(a_4=(3\times4-2)^2=(12-2)^2=10^2=100\). Therefore, 100 is the correct option. \(121\) would result only if the expression inside the square were 11, which it is not here. Exam tip: substitute the value of \(n\) first, then simplify the bracket before applying the exponent.
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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