2/3+2/3×5+2/5×7+2/7×9+2/9×11+2/11储恭臂枷赚磺辫委播莲×13=1-1/3+1/3-1/5+1/5-1/7+1/7-1/9+1/9-1/11+1/11-1/13=1-1/13=12/13
亲,*^__^*,不懂请追问,满意请点击 设为满意答案,谢谢!