作业帮(1/4+1/5+1/6+...+1/671)(1/3+1/4+1/5+...+1/670)-(1/3+1/4+1/5+...+1/671)(1/4+1/5+1/6+...+1/670)=
来源：学生作业帮助网 编辑：作业帮 时间：2024/11/16 23:50:47
xQK ,E~j]
O
Rt.}g 8Hc<7NdE{yPlYSݺ+0x=$ r[
Hp@ kZp\vv_Z_MiZUAEITbs ç}
(1/4+1/5+1/6+...+1/671)(1/3+1/4+1/5+...+1/670)-(1/3+1/4+1/5+...+1/671)(1/4+1/5+1/6+...+1/670)=
(1/4+1/5+1/6+...+1/671)(1/3+1/4+1/5+...+1/670)-(1/3+1/4+1/5+...+1/671)(1/4+1/5+1/6+...+1/670)=
(1/4+1/5+1/6+...+1/671)(1/3+1/4+1/5+...+1/670)-(1/3+1/4+1/5+...+1/671)(1/4+1/5+1/6+...+1/670)=
=(1/4+...+1/670 + 1/671) (1/3+...+1/670) - (1/3+ ...+ 1/670 + 1/671) (1/4+ ...+1/670)
=(1/4+...+1/670) * (1/3+...+1/670) + 1/671* (1/3+...+1/670) - (1/3+ ...+1/670) * (1/4+ ...+1/670) - 1/671*(1/4+ ...+1/670)
=1/671* (1/3+...+1/670) - 1/671*(1/4+ ...+1/670)
=1/671 * (1/3 + ...1/670 - (1/4+ ...+1/670))
=1/671 * (1/3-1/4)
=1/(671*12)
=1/8052