JEE Mains · Maths · STD 11 - 8. sequence and series
Let \(S=2+\frac{6}{7}+\frac{12}{7^{2}}+\frac{20}{7^{3}}+\frac{30}{7^{4}}+\ldots . .\) then \(4 S\) is equal to
- A \(\left(\frac{7}{3}\right)^{2}\)
- B \(\frac{7^{3}}{3^{2}}\)
- C \(\left(\frac{7}{3}\right)^{3}\)
- D \(\frac{7^{2}}{3^{3}}\)
Answer & Solution
Correct Answer
(C) \(\left(\frac{7}{3}\right)^{3}\)
Step-by-step Solution
Detailed explanation
\(S=2+\frac{6}{7}+\frac{12}{7^{2}}+\frac{20}{7^{3}}+\frac{30}{7^{4}}+\ldots \ldots\) Considering infinite sequence, \(S =2+\frac{6}{7}+\frac{12}{7^{2}}+\frac{20}{7^{3}}+\frac{30}{7^{4}}+\ldots \ldots \ldots\)…
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