Not able to find the solution for the following question?

Asked by vishal | 6th Jul, 2013, 02:43: PM

Expert Answer:

take 7 common
then
7(1+11+111+....................upto n terms)
multiply and divide by 9
7/9(9+99+999+................... nterms)
7/9[(10-1)+(100-1)+(1000-1)+.................. nterms)
applying geometric series sum formula for n terms
7/9[10(10^n-1/9)-n]
7/81[10^(n+1)-9n-10]

Answered by  | 6th Jul, 2013, 05:54: PM

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