求:-4.2+5.7-8.4+10 -1/4+5/6+2/3-1/2 12-(-18)+(-7)-15 4.7-(-8.9)-7.5+(-6)的简便算法!

问题描述:

求:-4.2+5.7-8.4+10 -1/4+5/6+2/3-1/2 12-(-18)+(-7)-15 4.7-(-8.9)-7.5+(-6)的简便算法!

-4.2+5.7-8.4+10
=5.7-4.2+10-8.4
=1.5+1.6
=3.1
-1/4+5/6+2/3-1/2
=5/6+4/6-1/4-1/2
=9/12-3/4
=3/4-3/4
=0
12-(-18)+(-7)-15
=12-7+18-15
=5+3
=8
4.7-(-8.9)-7.5+(-6)
=4.7+8.9-7.5-6
=4.7+1.4-6
=6.1-6
=0.1帅锅或美女,第二道题错了,麻烦改一改吧!我好确定标准答案!-1/4+5/6+2/3-1/2=5/6+4/6-1/4-1/2=9/6-3/4=3/2-3/4=6/4-3/4=3/4