Sum of first n natural no. Is S ans S=n(n+1)/2. If S=55 then find value of n.
Answers
Answered by
0
Answer:
10
Step-by-step explanation:
S= n/2+(2a+(n-1)d)
55= n/2 + (2 + (n-1))
110= 2n-n+n²
n²+n-110=0
n²+11n-10n-110=0
n(n+11) -10(n+11)=0
n= 10, -11
n≠ -11
so the value of n is 10
Answered by
0
Step-by-step explanation:
55=n(n+1)/2
110=n²+n
n²+n-110=0
n²+11n-10n-110=0
n(n+11)-10(n+11)=0
n=10
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