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Question

Question: If [x] denotes the greatest integer £ x, then \({\lim_{n \rightarrow \infty}}^{\frac{1}{n^{3}}}\){[...

If [x] denotes the greatest integer £ x, then

limn1n3{\lim_{n \rightarrow \infty}}^{\frac{1}{n^{3}}}{[12x] + [22x] + [32x] + ….+ [n2x]} equals :

A

x/2

B

x/3

C

x/6

D

0

Answer

x/3

Explanation

Solution

xĪI, [x] = x

Limn12x+22x+.....+n2xn3\underset{n \rightarrow \infty}{Lim}\frac{1^{2}x + 2^{2}x + ..... + n^{2}x}{n^{3}}ŽLimnx(12+22+.....+n2)n3\underset{n \rightarrow \infty}{Lim}\frac{x(1^{2} + 2^{2} + ..... + n^{2})}{n^{3}}

= x. 13\frac{1}{3} (difference of power of Nr and Nr is one)