If \(a_n=7\cdot3^{n-1}\), what is the fourth term?
Answer and explanation
Correct answer: 189
For the fourth term, substitute \(n=4\): \(a_4=7\cdot3^{4-1}=7\cdot3^3=7\cdot27=189\). Therefore, 189 is correct. The value 63 may result from incorrectly using \(7\cdot3^2\). Exam tip: In a general-term formula, substitute the term number first and simplify the exponent carefully.
Frequently asked questions
What is the correct answer to this question?
189
Why is this the correct answer?
For the fourth term, substitute \(n=4\): \(a_4=7\cdot3^{4-1}=7\cdot3^3=7\cdot27=189\). Therefore, 189 is correct. The value 63 may result from incorrectly using \(7\cdot3^2\). Exam tip: In a general-term formula, substitute the term number first and simplify the exponent carefully.
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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