Let, f(1)=1 and f(n)=2 _ r=1 ^ n-1 f(r) . Then, _ n=1 ^ m f(n) is equal to
Mathematics · JEE Main · NTA Exams — Progression and Series
Let, \(f(1)=1\) and \(f(n)=2 \sum_{r=1}^{n-1} f(r)\). Then, \(\sum_{n=1}^{m} f(n)\) is equal to
- \(3^{m}\)
- \(3^{m}-1\)
- \(3^{m-1}\)
- None of these
Answer
(B) 3^ m -1
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