把下列各式写成省略括号和加号的形式.(1)(-12)-(+8)+(-6)-(-5);(2)(+3.7)-(-2.1)-1.8+

问题描述:

把下列各式写成省略括号和加号的形式.(1)(-12)-(+8)+(-6)-(-5);(2)(+3.7)-(-2.1)-1.8+
(-2.6);(3)(-1.2)-(-2.1)+(-10.2)-(+0.5)

(1)(-12)-(+8)+(-6)-(-5)=-12-8-6+5=-20-6+5=-26+5=-21(2)(+3.7)-(-2.1)-1.8+(-2.6)=3.7+2.1-1.8-3.6=3.7-3.6+2.1-1.8=0.1+2.1-1.8=2.2-1.8=0.4(3)(-1.2)-(-2.1)+(-10.2)-(+0.5)=-1.2+2...