2 ways: 1+3+5+ ... +(2n-1) + (2n+1) + (2n-1)+ ... +5+3+1 = n^2 + (n+1)^2si118yt118si (61)in #steem • 4 years ago #steemstem #steemit-education #knowledge #steemeducation #steemtrail #stem