题目内容
脱式计算,能简算的要简算.
(1)
×[
-(
-
)]
(2)4-
÷4-
(3)
×(
+
)+
(4)2.4-8.9×(4.5-4.5)
(1)
5 |
18 |
3 |
4 |
11 |
20 |
1 |
4 |
(2)4-
4 |
5 |
4 |
5 |
(3)
12 |
5 |
5 |
6 |
3 |
4 |
4 |
5 |
(4)2.4-8.9×(4.5-4.5)
考点:分数的四则混合运算,分数的简便计算
专题:运算顺序及法则,运算定律及简算
分析:(1)中括号里面根据减法的性质进行简算,最后算乘法;
(2)先算除法,再减法的性质进行简算;
(3)根据乘法分配律和加法结合律进行简算;
(4)先算小括号里面的减法,再算乘法,最后算小括号外面的减法.
(2)先算除法,再减法的性质进行简算;
(3)根据乘法分配律和加法结合律进行简算;
(4)先算小括号里面的减法,再算乘法,最后算小括号外面的减法.
解答:
解:(1)
×[
-(
-
)]
=
×[
-
+
]
=
×[
+
-
]
=
×[1-
]
=
×
=
;
(2)4-
÷4-
=4-
-
=4-(
+
)
=4-1
=3;
(3)
×(
+
)+
=
×
+
×
+
=2+
+
=2+(
+
)
=2+2
=4
;
(4)2.4-8.9×(4.5-4.5)
=2.4-8.9×0
=2.4-0
=2.4.
5 |
18 |
3 |
4 |
11 |
20 |
1 |
4 |
=
5 |
18 |
3 |
4 |
11 |
20 |
1 |
4 |
=
5 |
18 |
3 |
4 |
1 |
4 |
11 |
20 |
=
5 |
18 |
11 |
20 |
=
5 |
18 |
9 |
20 |
=
1 |
8 |
(2)4-
4 |
5 |
4 |
5 |
=4-
1 |
5 |
4 |
5 |
=4-(
1 |
5 |
4 |
5 |
=4-1
=3;
(3)
12 |
5 |
5 |
6 |
3 |
4 |
4 |
5 |
=
12 |
5 |
5 |
6 |
12 |
5 |
3 |
4 |
4 |
5 |
=2+
9 |
5 |
4 |
5 |
=2+(
9 |
5 |
4 |
5 |
=2+2
3 |
5 |
=4
3 |
5 |
(4)2.4-8.9×(4.5-4.5)
=2.4-8.9×0
=2.4-0
=2.4.
点评:考查了运算定律与简便运算,四则混合运算.注意运算顺序和运算法则,灵活运用所学的运算定律简便计算.
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