利用加法运算律简便运算.(1)(-5)+3+(+5)+(-2);(2)(?312)+(+67)+(?0.5)+(+117);(3)4.5+(?2

2025-04-24 16:57:28
推荐回答(1个)
回答1:

(1)(-5)+3+(+5)+(-2)
=(-5+5)+(3-2)
=0+1
=1;

(2)(?3

1
2
)+(+
6
7
)+(?0.5)+(+1
1
7
)
=(-3.5-0.5)+(
6
7
+1
1
7

=-4+2
=-2;

(3)4.5+(?2.5)+9
1
3
+(?15
2
3
)+2
1
3

=(4.5-2.5)+(9
1
3
-15
2
3
+2
1
3

=2-4
=-2.