JEE Mains · Maths · STD 11 - 1. set theory
The number of elements in the set \(\left\{ n \in N : 10 \leq n \leq 100\right.\) and \(3^{ n }-3\) is a multiple of \(7\}\) is \(........\).
- A \(15\)
- B \(14\)
- C \(13\)
- D \(12\)
Answer & Solution
Correct Answer
(A) \(15\)
Step-by-step Solution
Detailed explanation
\(n \in[10,100]\) \(3^{ n }-3 \text { is multiple of } 7\) \(3^{ n }=7 \lambda+3\) \(n =1,7,13,20, \ldots .97\) Number of possible values of \(n=15\)
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