化简下列各数,并发现规律:
(1)-(+3)=______;+(-4)=______;+(+2)=______;-(-4)=______.
(2)-[-(-3)]=______;
-[+(-3.5)]=______;
+[-(-6)]=______;
-[-(+7)]=______.
(3)观察上述填空,你能发现什么规律?
网友回答
解:(1)-(+3)=-3;+(-4)=-4;+(+2)=2;-(-4)=4.
(2)-[-(-3)]=-3;
-[+(-3.5)]=3.5;
+[-(-6)]=6;
-[-(+7)]=7.
(3)规律:负号的个数为奇数,结果是负数,负号的个数是偶数,结果是正数.
解析分析:(1)(2)根据相反数的定义解答;
(3)根据计算,从负号的个数考虑规律.
点评:本题考查了相反数,是基础题,熟记概念是解题的关键.