1/2+1/6+1/18+1/54+1/162+1/486=?
问题描述：
1/2+1/6+1/18+1/54+1/162+1/486=?
答
182/243
答
333/486=111/162
答
121/81
答
243分之182
答
设s=1/2+1/6+1/18+1/54+1/162+1/486
3s=3/2+1/2+1/6+1/18+1/54+1/162
3s-s=1-1/486
2s=485/486
s=485/972
1/2+1/6+1/18+1/54+1/162+1/486=485/972
答
1/2+1/6+1/18+1/54+1/162+1/486
=（1+3+9+27+81+243）/486
=364/486