Prove that n N.
L.H.S =
=
since = 1
= i
= -1
= i – 1 – i + 1 + i - 1……+i-1
As, all terms will get cancel out consecutively except the first two terms. so that will get remained will be the answer.
= i - 1
L.H.S = R.H.S
Hence proved.