用简便方法:|4/5-3/7|+4/7-2/3|-|1/3-1/5|

问题描述:

用简便方法:|4/5-3/7|+4/7-2/3|-|1/3-1/5|

因为4/5>3/7,4/71/5
所以,原式=4/5-3/7+2/3-4/7-1/3+1/5
=(4/5+1/5)-(3/7+4/7)+(2/3-1/3)
=1-1+1/3
=1/3