Question

Q5. Sum of 1 to n natural numbers is 36, then find the value of n.​

Answer 1

using formula

Sn =n(n+1)/2

36=n(n+1)/2

72=n^2 +n

n^2 +9n-8n-72=0

(n+9)(n-8) =0

so, n=9

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