题目内容
(2012?洪山区一模)能简便计算的用简便方法计算.
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分析:(1)(5)依据四则运算计算顺序,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解答,
(2)(3)(4)运用乘法分配律间的,
(6)化
=1-
,
=
-
,
=
-
,
=
-
…
=
-
即可解答.
(2)(3)(4)运用乘法分配律间的,
(6)化
1 |
2 |
1 |
2 |
1 |
6 |
1 |
2 |
1 |
3 |
1 |
12 |
1 |
3 |
1 |
4 |
1 |
20 |
1 |
4 |
1 |
5 |
1 |
90 |
1 |
9 |
1 |
10 |
解答:解:(1)
÷
×
,
=
×
,
=1
;
(2)
×
+0.25×
-
,
=0.25×(
+
-1),
=0.25×0,
=0;
(3)(
+
)÷
,
=
×
+
×
,
=1
+1,
=2
;
(4)
×
+
÷
,
=
×(
+
),
=
×
,
=
;
(5)
÷[(
+
)×
],
=
÷[
×
],
=
÷
,
=3;
(6)
+
+
+
+…
,
=1-
+
-
+
-
+
-
…+
-
,
=1-
,
=
.
10 |
13 |
35 |
26 |
7 |
3 |
=
4 |
7 |
7 |
3 |
=1
1 |
3 |
(2)
4 |
7 |
1 |
4 |
3 |
7 |
1 |
4 |
=0.25×(
4 |
7 |
3 |
7 |
=0.25×0,
=0;
(3)(
7 |
8 |
13 |
16 |
13 |
16 |
=
7 |
8 |
16 |
13 |
13 |
16 |
16 |
13 |
=1
1 |
13 |
=2
1 |
13 |
(4)
1 |
7 |
5 |
12 |
5 |
12 |
7 |
5 |
=
5 |
12 |
1 |
7 |
5 |
7 |
=
5 |
12 |
6 |
7 |
=
5 |
14 |
(5)
1 |
5 |
2 |
3 |
1 |
5 |
1 |
13 |
=
1 |
5 |
13 |
15 |
1 |
13 |
=
1 |
5 |
1 |
15 |
=3;
(6)
1 |
2 |
1 |
6 |
1 |
12 |
1 |
20 |
1 |
90 |
=1-
1 |
2 |
1 |
2 |
1 |
3 |
1 |
3 |
1 |
4 |
1 |
4 |
1 |
5 |
1 |
9 |
1 |
10 |
=1-
1 |
10 |
=
9 |
10 |
点评:本题考查知识点:(1)依据四则运算顺序正确进行计算,(2)正确运用简便算法解决问题.
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