Question

一道数学问题求简便算式和过程！

3分之2+9分之2+27分之2+81分之2+243分之2

Answer 1

解：
（2/3)+(2/9)+(2/27)+(2/81)+(2/243)
=(81x2+27x2+9x2+3x2)/243
=2x(81+27+9+3)/243
=2x120/243
=240/243

Answer 2

2/3+2/9+2/27+2/81+2/243=2(1/3+1/9+1/27+1/81+1/243)=2*(1/3)(1-1/3^5)/(1-1/3)
=1-1/3^5=1-1/243=242/243

Answer 3

原式=(1-1/3)+(1/3-1/9)+(1/9-1/27)+(1/27-1/81)+(1/81-1/243)
=1-1/243
=242/243
我想这样比较简便！