题目内容
脱式计算
(1)
+
-
×6
(2)
÷
+
×
(3)(
+
-
)÷
×20;
(4)[4-(
-
)]×
(5)[2-(
+
)]÷
(6)(
×
-
)×21.
(1)
4 |
15 |
1 |
3 |
1 |
12 |
(2)
7 |
9 |
11 |
5 |
2 |
9 |
5 |
11 |
(3)(
5 |
12 |
1 |
6 |
7 |
12 |
1 |
7 |
(4)[4-(
3 |
4 |
3 |
8 |
4 |
29 |
(5)[2-(
1 |
4 |
3 |
8 |
1 |
4 |
(6)(
7 |
15 |
5 |
14 |
1 |
7 |
分析:(1)(3)(4)(5)(6)依据四则运算顺序:先算第二级运算,再算第一级运算,如果只含有同一级运算,按照从左到右顺序计算,有括号先算括号里面的顺序解答即可解答,
(2)运用乘法分配律解答.
(2)运用乘法分配律解答.
解答:解:(1)
+
-
×6,
=
+
-
,
=
-
,
=
;
(2)
÷
+
×
,
=(
+
)×
,
=1×
,
=
;
(3)(
+
-
)÷
×20,
=(
-
)÷
×20,
=0÷
×20,
=0;
(4)[4-(
-
)]×
,
=[4-
]×
,
=
×
,
=
;
(5)[2-(
+
)]÷
,
=[2-
]÷
,
=
÷
,
=
;
(6)(
×
-
)×21,
=(
-
)×21,
=
×21,
=
.
4 |
15 |
1 |
3 |
1 |
12 |
=
4 |
15 |
1 |
3 |
1 |
2 |
=
9 |
15 |
1 |
2 |
=
1 |
10 |
(2)
7 |
9 |
11 |
5 |
2 |
9 |
5 |
11 |
=(
7 |
9 |
2 |
9 |
5 |
11 |
=1×
5 |
11 |
=
5 |
11 |
(3)(
5 |
12 |
1 |
6 |
7 |
12 |
1 |
7 |
=(
7 |
12 |
7 |
12 |
1 |
7 |
=0÷
1 |
7 |
=0;
(4)[4-(
3 |
4 |
3 |
8 |
4 |
29 |
=[4-
3 |
8 |
4 |
29 |
=
29 |
8 |
4 |
29 |
=
1 |
2 |
(5)[2-(
1 |
4 |
3 |
8 |
1 |
4 |
=[2-
5 |
8 |
1 |
4 |
=
11 |
8 |
1 |
4 |
=
11 |
2 |
(6)(
7 |
15 |
5 |
14 |
1 |
7 |
=(
1 |
6 |
1 |
7 |
=
1 |
42 |
=
1 |
2 |
点评:(1)依据四则运算顺序正确进行计算,(2)运用乘法分配律正确解决问题,是本题考查知识点.
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