Question

If the sum of first 'n' natural number is 1/5 times the sum of their squares , then find the value of n .​

Answer 1

Answer:

Formula:- x = x

:- n = n

Step-by-step explanation:

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Answer 2

Answer:

Sum of first n natural numbers = n(n+1)/2

Sum of squares of n natural numbers = n(n+1)(2n+1)/6

Given sum of the first n natural numbers is 1/5 times the sum of their squares.

So n(n+1)/2 = (1/5)n(n+1)(2n+1)/6

15 = 2n+1

2n = 14

n = 7