题目内容

(2013?湖南)(1)
3
8
+0.37=
0.745
0.745

(2)2
2
9
÷[3
1
6
-(3.4-2
2
3
)]
(3)(
1
3
+
1
4
+
1
8
)×24
(4)
1
2015
+
3
2015
+
5
2015
+…+
2013
2015
+1
(5)
1
3×4
+
1
4×5
+
1
5×6
+…+
1
17×18

(6)
1
8
×34.5-
3
8
×3.5
(7)
44
55
×37
(8)27×
15
26

(9)(1+
1
2
+
1
3
)×(
1
2
+
1
3
=
1
4
)-(1+
1
2
+
1
3
+
1
4
)×(
1
2
+
1
3

(10)(1-
1
3
)×(1-
1
4
)×(1-
1
5
)×…×(1-
1
50
分析:(1)先把分数变成小数再计算;
(2)先算小括号里面的减法,再算中括号里面的减法,最后算括号外的除法,注意把小数化成分数再计算;
(3)运用乘法分配律简算;
(4)根据同分母分数的加法的计算方法,分母不变,分子相加,把分子看成一个首项是1,末项是2015,等差是2的等差数列,再根据等差数列的求和公式,求出分子的和,进而求解;
(5)
1
3×4
=
1
3
-
.
14
1
4×5
=
1
4
-
1
5
1
17×18
=
1
17
-
1
18
,由此化简求解;
(6)先运用积不变的规律,把
3
8
×3.5变成
1
8
×10.5,再运用乘法分配律简算;
(7)先把分数化简,再计算;
(8)先把27分解成26+1,再运用乘法分配律简算;
(9)令
1
2
+
1
3
=a,然后运用乘法分配律化简,再相减即可求解;
(10)先求出小括号里面的差,再约分求解即可.
解答:解:(1)
3
8
+0.37,
=0.375+0.37,
=0.745;

(2)2
2
9
÷[3
1
6
-(3.4-2
2
3
)],
=2
2
9
÷[3
1
6
-
11
15
],
=2
2
9
÷
73
30

=
200
219


(3)(
1
3
+
1
4
+
1
8
)×24,
=
1
3
×24+
1
4
×24+
1
8
×24,
=8+6+3,
=17;

(4)
1
2015
+
3
2015
+
5
2015
+…+
2013
2015
+1,
=
1+3+5+…+2015
2015

=
(1+2015)×1008÷2
2015

=
1016064
2015


(5)
1
3×4
+
1
4×5
+
1
5×6
+…+
1
17×18

=
1
3
-
1
4
+
1
4
-
1
5
+
1
5
-
1
6
+…+
1
17
-
1
18

=
1
3
-
1
18

=
5
18


(6)
1
8
×34.5-
3
8
×3.5,
=
1
8
×34.5-(
3
8
÷3)×(3.5×3),
=
1
8
×34.5-
1
8
×10.5,
=
1
8
×(34.5-10.5),
=
1
8
×24,
=3;

(7)
44
55
×37,
=
4
5
×37,
=
148
5


(8)27×
15
26

=(26+1)×
15
26

=26×
15
26
+1×
15
26

=15+
15
26

=15
15
26


(9)令
1
2
+
1
3
=a,那么:
(1+
1
2
+
1
3
)×(
1
2
+
1
3
+
1
4
)-(1+
1
2
+
1
3
+
1
4
)×(
1
2
+
1
3
),
=(1+a)×(a+
1
4
)-(1+
1
4
+a)×a,
=(a+a2+
1
4
a+
1
4
)-(a+
1
4
a+a2),
=a+a2+
1
4
a+
1
4
-a-
1
4
a-a2
=(a-a)+(a2-a2)+(
1
4
a-
1
4
a)+
1
4

=0+0+0+
1
4

=
1
4


(10)(1-
1
3
)×(1-
1
4
)×(1-
1
5
)×…×(1-
1
50
),
=
2
3
×
3
4
×
4
5
×…
48
49
×
49
50

=
2
50

=
1
25
点评:完成本题要注意分析式中数据,运用合适的简便方法计算.
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