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Grade 12Differential Calculus

Solve using Sandwich Theorem-

lim (n tends to infinity) 1 + 1/2^2+ 1/3^2+ 1/4^2 +....+1/n^2

Profile image of Pallabi Mishra
16 Years agoGrade 12
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1 Answer

Profile image of Jitender Singh
11 Years ago
Ans:
L = \lim_{n\rightarrow \infty }\sum_{r=1}^{n}(\frac{1}{r^{2}})
\frac{1}{r^{3}}<\frac{1}{r^{2}}<1
\sum \frac{1}{r^{3}}<\sum \frac{1}{r^{2}}<\sum 1
\lim_{n\rightarrow \infty }\sum_{r=1}^{n}1 = \infty
\lim_{n\rightarrow \infty }\sum_{r=1}^{n}(\frac{1}{r^{3}})
This is a divergent series, so it will also tend to infinity.
Acording to sandwich theorm, L will also approaches to infinity.
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Jitender Singh
IIT Delhi
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