题目内容
怎样算便怎样算:
|
|
(
|
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(
|
2008×
|
|
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
分析:(1)把除法变为乘法,运用乘法分配律简算.
(2)先算括号内的,再算括号外的.
(3)运用乘法分配律简算.
(4)把除法变为乘法,运用乘法交换律与结合律简算
(5)先算括号内的,再算括号外的.
(6)把2008看作2007+1,运用乘法分配律简算.
(7)先算括号内的,再算乘法,最后算加法.
(2)先算括号内的,再算括号外的.
(3)运用乘法分配律简算.
(4)把除法变为乘法,运用乘法交换律与结合律简算
(5)先算括号内的,再算括号外的.
(6)把2008看作2007+1,运用乘法分配律简算.
(7)先算括号内的,再算乘法,最后算加法.
解答:
解:(1)
÷
+
×
=
×
+
×
=(
+
)×
=1×
=
;
(2)
÷(
+
)
=
÷
=
×
=
;
(3)(
+
)×4
=
×4+
×4
=
+1
=1
;
(4)
×
÷
×
=
×
×
×
=(
×
)×(
×
)
=1×
=
;
(5)(
+
)÷
=
×
=
;
(6)2008×
=(2007+1)×
=2007×
+
=2006+
=2006
;
(7)
+(
+
)×
=
+
×
=
+
=
.
7 |
9 |
11 |
5 |
2 |
9 |
5 |
11 |
=
7 |
9 |
5 |
11 |
2 |
9 |
5 |
11 |
=(
7 |
9 |
2 |
9 |
5 |
11 |
=1×
5 |
11 |
=
5 |
11 |
(2)
2 |
5 |
3 |
4 |
2 |
5 |
=
2 |
5 |
23 |
20 |
=
2 |
5 |
20 |
23 |
=
8 |
23 |
(3)(
1 |
8 |
1 |
4 |
=
1 |
8 |
1 |
4 |
=
1 |
2 |
=1
1 |
2 |
(4)
7 |
8 |
5 |
7 |
7 |
8 |
5 |
7 |
=
7 |
8 |
5 |
7 |
8 |
7 |
5 |
7 |
=(
7 |
8 |
8 |
7 |
5 |
7 |
5 |
7 |
=1×
25 |
49 |
=
25 |
49 |
(5)(
7 |
8 |
13 |
16 |
13 |
16 |
=
27 |
16 |
16 |
13 |
=
27 |
13 |
(6)2008×
2006 |
2007 |
=(2007+1)×
2006 |
2007 |
=2007×
2006 |
2007 |
2006 |
2007 |
=2006+
2006 |
2007 |
=2006
2006 |
2007 |
(7)
2 |
3 |
4 |
7 |
1 |
2 |
7 |
25 |
=
2 |
3 |
15 |
14 |
7 |
25 |
=
2 |
3 |
3 |
10 |
=
29 |
30 |
点评:考查了分数的四则混合运算,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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