This is the Important question based on Arithmetic progression Chapter of R.S Aggarwal book for ICSE & CBSE Board.

In this Question you have to find the sum upto n terms.

This is the Question Number 32 Of Exercise 11 C of RS Aggarwal Solution

# Find the sum of the following : (1-1/n)+(1-2/n)+(1-3/n)+……upto n terms.

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According to the Question:

a=1-1/n

a=(n-1)/n

d=1-2/n-1+1/n

d=1/n

Sum

=n/2(2a+(n-1)d)

=n/2[2(n-1)/n+(n-1)-1/n]

=n/2{[2(n-1)-(n-1)]/n]}

=n/2[(n-1)/n]

=1/2(n-1)