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+(?2.5)+913+(?1523)+213.
(1)(-5)+3+(+5)+(-2)
=(-5+5)+(3-2)
=0+1
=1;
(2)(?3
)+(+
)+(?0.5)+(+1
)
=(-3.5-0.5)+(
+1
)
=-4+2
=-2;
(3)4.5+(?2.5)+9
+(?15
)+2
=(4.5-2.5)+(9
-15
+2
)
=2-4
=-2.
=(-5+5)+(3-2)
=0+1
=1;
(2)(?3
1 |
2 |
6 |
7 |
1 |
7 |
=(-3.5-0.5)+(
6 |
7 |
1 |
7 |
=-4+2
=-2;
(3)4.5+(?2.5)+9
1 |
3 |
2 |
3 |
1 |
3 |
=(4.5-2.5)+(9
1 |
3 |
2 |
3 |
1 |
3 |
=2-4
=-2.
温馨提示:答案为网友推荐,仅供参考