Plz explain how to solve dis...
Q.3. k = 1 n k 1 + 1 n k - 1 =

Hi, After expanding it will be S=               1+21+1n+31+1n2+41+1n3+..........+n1+1nn-11+1nS=          1+1n+21+1n2+31+1n3+.......+n-11+1nn-1+n1+1nnSubtracting, S1-1-1n= 1+1+1n+1+1n2+1+1n3+....+1+1nn-1 +n1+1nnNow, 1+1+1n+1+1n2+1+1n3+....+1+1nn-1 is a GP with a =1 and r = 1+1n-Sn=11+1nn-11+1n-1+n1+1nnS= -n2×1+1nn-1+n1+1nn

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