find the sum of first n term of the series 6+66+666+......
Anonymous:
ans simple h
6 common lu then u will see . it will became .. natural numm sum of natural num ka formula ise krna then
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6 / 9 [ ( 10 - 1 ) + ( 10^2 - 1 ) + ( 10^3 - 1 )....]
=> Sn = 6 / 9 [ ( 10 + 10^2 + 10^3...) - n ]
=> Sn = 6 / 9 [ 10 { 10^n - 1 } / { 10 - 1 } - n ]
=> Sn = 6 / 9 [ 10 / 9 { 10^n - 1 } - n ]
=> Sn = 6 / 81 [ 10 ^ ( n + 1 ) - 9n - 10 ]
=> Sn = 6 / 9 [ ( 10 + 10^2 + 10^3...) - n ]
=> Sn = 6 / 9 [ 10 { 10^n - 1 } / { 10 - 1 } - n ]
=> Sn = 6 / 9 [ 10 / 9 { 10^n - 1 } - n ]
=> Sn = 6 / 81 [ 10 ^ ( n + 1 ) - 9n - 10 ]
its right as well
??
nothing
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