1-1/3-1/9-1/27-1/81-1/243-1/729-1/2187
1-1/3-1/9-1/27-1/81-1/243-1/729-1/2187
巧算:1+3+9++27+81+243+729+2187
计算:3/1+9/1+27/1+81/1+243/1+729/1+2187/1
1+3+9+27+81+243+729
用错位相减法算 (1)3+9+27+81+243+729+2187的和
计算:1+3+9+27+81+243+729+2187+6561+19683!
找规律2187,729,243,81,( ),( ),3,1
求1+1/3+1/9+1/27+1/81+...+1/243+1/729
计算:1+1/3+1/9+1/27+1/81+1/243+1/729
1-1/3-1/9-1/27-1/81-1/243-1/729=?
计算:1-1/3-1/9-1/27-1/81-1/243-1/729
3/1+9/1+27/1+81/1+243/1+729/1怎么算?