\xa0Find the sum of (1− 1) + (1− 2) + (1− 3) ……. upto n terms. n n n

\xa0Find the sum of (1− 1) + (1− 2) + (1− 3) ……. upto n term

1.	\xa0Find the sum of (1− 1) + (1− 2) + (1− 3) ……. upto n terms. n n n
Answer» We can write the given series as:(1+1+1+.....+n) - (1+2+3+........+n)= 1 X n - Sn= n -\xa0{tex}{ n (n+1) \\over 2}{/tex}=\xa0{tex}{n-n^2\\over 2}{/tex}