(1/5+1/7+1/9+1/11)(1/7+1/9+1/11+1/13)-(1/5+1/7+1/9+1/11+1/13)(1/7+1/9+1/11)简便运算

来源：学生学帮网编辑：学帮网时间：2024/06/02 08:59:58

(1/5+1/7+1/9+1/11)*(1/7+1/9+1/11+1/13)-(1/5+1/7+1/9+1/11+1/13)*(1/7+1/9+1/11)
简便运算

提取=(1/5+1/7+1/9+1/11)*(1/7+1/9+1/11)+(1/5+1/7+1/9+1/11)*1/13-(1/5+1/7+1/9+1/11)*(1/7+1/9+1/11)-1/13*(1/7+1/9+1/11)=(1/5+1/7+1/9+1/11)*1/13-1/13*(1/7+1/9+1/11)=1/13*(1/5+1/7+1/9+1/11-1/7+1/9+1/11）=1/13*1/5=1/65