—(2/13+8/15)+(2/13-7/15)简便计算

问题描述:

—(2/13+8/15)+(2/13-7/15)简便计算

2/13-7/15-2/13-8/15=-7/15-8/15=-1

=-2/13+8/15+2/13-7/15
=-2/13+2/13+8/15-7/15
=1/15

—(2/13+8/15)+(2/13-7/15)
=-2/13+2/13-(8/15+7/15)
=0-1
=-1

—(2/13+8/15)+(2/13-7/15)
=—2/13-8/15+2/13-7/15
=(—2/13+2/13)-(8/15+7/15)
=0-1
=-1