计算
(1)(+7)+(-6)+(-7)+(+6);
(2)(-2.6)+(-3.4)+(+2.3)+1.5-2.3;
(3);
(4)(+9)+(-7)+(+10)+(-3)+(-9);
(5)(-26.54)+(-6.4)+(-18.54)+6.4;
(6)(-3.75)+2.85+(-1)-+3.15+(-2.5).
网友回答
解:(1)原式=[(-6)+(+6)]+[(+7)+(-7)],
=0+0,
=0;
(2)原式=[(-2.6)+(-3.4)]+1.5+[(+2.3)+(-2.3)],
=-6+1.5+0,
=-4.5;
(3)原式=[(-3)+2]+[(-1)+3],
=-1+2,
=1;
(4)原式=9+(-7)+10+(-3)+(-9),
=[(-7)+(-3)+10]+[(-9)]+9],
=0;
(5)原式=[(-26.54)+(-18.54)]+[6.4+(-6.4)],
=-45.08+0,
=-45.08;
(6)原式=(-3.75)+2.85+(-1)+(-)+3.15+(-2.5),
=[(-3.75)+(-1)+(-)+(-2.5)]+(2.85+3.15),
=-8+6,
=-2;
解析分析:(1)(2)(4)(5)先将互为相反数的两数相加;
(3)先将同分母的分数相加;
(6)将分数化为小数,再相加即可.
点评:解题关键是综合应用加法交换律和结合律,简化计算.注意题中是否有互为相反数,如(-9)和9,其和为0.