JEE Mains · Maths · STD 11 - 12. limits
Let [ ] denote the greatest integer function and \( f(x)=lim_{n\rightarrow\infty}\frac{1}{n^{3}}\sum_{k=1}^{n}[\frac{k^{2}}{3^{x}}] \) Then \( 12\sum_{j=1}^{x}f(j) \) is equal to ........... .
- A 1
- B 2
- C 3
- D 4
Answer & Solution
Correct Answer
(B) 2
Step-by-step Solution
Detailed explanation
\(\sum_{k=1}^n\left(\frac{k^2}{3^x}-1\right)<\sum_{k=1}^n\left[\frac{k^2}{3^x}\right] \leq \sum_{k=1}^n \frac{k^2}{3^x} \) \( \frac{n(n+1)(2 n+1)}{6 \cdot 3^x}<\sum_{k=1}^n\left[\frac{k^2}{3^x}\right] \leq \frac{n(n+1)(2 n+1)}{6 \cdot 3^x} \)…
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