(1-1/n)+( 1-2/n)+(1-3/n)+…… up to n terms=?	Choose the correct choice from the following:
A) 1/2n B) 1/2(n-1) C) 1/2n(n-1) D) none of these E) cannot be determined
Solution: Given sum=(1+1+1+…. to n terms)-(1/n+2/n+3/n+…. to n terms)   = n-(n(n+1)/2)/n   = n-(n+1)/2=1/2(n-1).   Answer 1/2(n-1)
<result>B</result>
(1-1/n)+( 1-2/n)+(1-3/n)+…… up to n terms=?