1+3+5+7+9+.+（2n+1）=[1+(2n+1)]+[3+(2n-1)]+[5+(2n-3)]+……=(2n+2)+(2n+2)+(2n+2)+……=(2n+2)×[(2n+1)+1]/4=(n+1)×(n+1)=(n+1)²很高兴为您解答,【the1900】团队为您答题.请点击下面的【选为满意回答】按...