(1)-4.2+5.7-8.4+10 (2)-1/4+5/6+2/3-1/2 (3)12+(-18)+(-7)-15 (4)4.7-(-8.9)-7.5+(-6)
问题描述:
(1)-4.2+5.7-8.4+10 (2)-1/4+5/6+2/3-1/2 (3)12+(-18)+(-7)-15 (4)4.7-(-8.9)-7.5+(-6)
答
-4.2+5.7-8.4+10=3.1
-1/4+5/6+2/3-1/2
=-3/12+10/12+8/12-6/12
=3/4
12+(-18)+(-7)-15
=12-18-7-15
=-28
4.7-(-8.9)-7.5+(-6)
=4.7+8.9-7.5-6
=0.1