(1/3)-(1/6)-(1/12)-(1/20)-(1/30)-(1/42)

计算：1/6-(+1/3)-(-1/12) 1/3+1/6+1/9+1/12+1/15 1+12+3+45+6 48*(1/12+1/6-3/4) (-1/6+3/4-1/12)*(-48) 1/3+1/6+1/12+...+1/9900 1/3-1/6-1/12-1/24 简便计算方法 1/(1*3) + 1/(3*6) + 1/(6*9) + 1/(9*12) + …+1/(96*99) 1/3+1/(3+6)+1/(3+6+9)+1/(3+6+9+12)+1/(3+6+9+12+15)+.1/(3+6+9+12+15+.96+99) 1/3+1/3+1/6+1/12+1/24+1/48+1/96 1/3+1/(3+6)+1/(3+6+9)+1/(3+6+9+12).+1/(3+6+9+.+99) 1/2+1/3+1/4+1/6+1/12+1/48+1/56 计算:1/3*6+1/6*9+1/9*12+.1/3n(3n+3) (-1/12-1/36+3/4-1/6)×(-48) (3/4-1/6-1/12-1/36)×(-48) (-1/12-1/36+3/4-1/6)*(-48) 3/(a+1)-12/(a²-1)-6/(1-a) (-1/6-1/16+3/4-1/12)*(-45)