Question

Find the sum of the following :
plzz solve this ..

Answer 1

as from pic we get 
a=(1-1/n)
d=-1/n
Sum of n terms=n/2(2a+(n-1)d)
                        =n/2(2(1-1/n)+(n-1)-1/n)
                        =n/2(2-2/n-1+1/n)
                        =n/2(1-1/n)
                        =n/2(n-1)n 
n get cancelled=(n-1)/2

:) Hope this ans would help u...

Answer 2

Required answer is (n-1)/2.