|(1/5)-(1/7)|+|(1/9)-(1/7)|+|(1/9)-(1/11)怎麼計算

|(1/5)-(1/7)|+|(1/9)-(1/7)|+|(1/9)-(1/11)怎麼計算

原式
=1/5-1/7+1/7-1/9+1/9-1/11
=1/5-1/11
=6/55