Question

Find the sum 1 /(1 + 2 )+ 1 /(1 + 2 + 3 )+ · · · + 1/( 1 + 2 + · · · + 51)​

Answer 1

Answer:

11+11+2+…+11+2+…+n

We know that1+2+…+n=n(n+1)2

Therefore, thenthterm is

Tn=1n(n+1)2=2n(n+1)=2(n+1−n)n(n+1)=2[1n−1n+1]

Step-by-step explanation:

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