1,1/2,1/3,1,1/9,2,( ),( ) 找规律

(1-1/2)*(1+1/2)*(1-1/3)*(1+1/3)*…*(1-1/9)*(1+1/9). |1-1/2|-|1/2-1/3|-|1/3-1/4|-.-|1/9-1/10| |1-1/2|+|1/2-1/3|+|1/3-1/4|+...|1/9-1/10| 1+2+3+.9 1+1+1+1+9+3+1+2 计算2/3(1+1/3)(1+1/9)(1+1/81)(1+1/81²) /1/3-1/2/+/1/4-1/3/+/1/5-1/4/+.+/1/10-1/9/ |1/3-1/2|+|1/4-1/3|+|1/5-1/4|+...+|1/10-1/9| ((1/2)-1)*((1/3)-1)*((1/4)-1)*((1/5)-1)*((1/6)-1)*((1/7)-1)*((1/8)-1)*((1/9)-1)*((1/10)-1) （1+1/2)*(1+1/4)*.*(1+1/10)*(1-1/3)*(1-1/5)*.(1-1/9)简算 (1-1/2^2)*(1-1/3)*(1-1/4^2)*…*(1-1/9^2)*(1/10^2) 1*2/1+2*3/1+3*4/1+...+8*9/1+9*10/1简算 9*(1-1/2)*(1-1/3)*(1-1/4)*(1-1/5)*(1-1/6)*(1-1/7)*(1-1/8)*(1-1/9)怎样简便计算 1:8 2:9 1:9 3:4 1:3 ... 因式分解；(1-1/2^2)(1-1/3^2)(1-1/4^2)...(1-1/9^2)(1-1/10^2)...(1-1/n^2) (1/7-1/9+1/21) /1/63+(-2)^3 1,1/2.1/3,1,1/9,2,( ),( ) 有理数:-1/2+1/3-(-1/9)-1/4=