The sum of infinity of the series 11+11+2+11+2+3 .......... is equal to .......... .
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Solution
Denominator of nth term is sum of first n natural numbers i.e (n)(n+1)2 nth term of equation Tn=1n(n+1)2=2n(n+1)=2n−2n+1 Sum of n terms Sn=∑Tn=21−22+22−23..........+2n−2n+1 ⇒Sn=2−2n+1⇒S∞=2