If \(a_n=5\cdot2^{n-1}-3\), what is the value of \(a_6\)?
Answer and explanation
Correct answer: 157
Substituting \(n=6\), \(a_6=5\cdot2^{6-1}-3=5\cdot2^5-3=5\cdot32-3=157\). Hence, 157 is correct. The close distractor 153 can result from mishandling the final \(-3\) or making an arithmetic error. Exam tip: substitute the term number into the exponent \(n-1\) first, then simplify step by step.
Frequently asked questions
What is the correct answer to this question?
157
Why is this the correct answer?
Substituting \(n=6\), \(a_6=5\cdot2^{6-1}-3=5\cdot2^5-3=5\cdot32-3=157\). Hence, 157 is correct. The close distractor 153 can result from mishandling the final \(-3\) or making an arithmetic error. Exam tip: substitute the term number into the exponent \(n-1\) first, then simplify step by step.
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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