题目内容
(1)
+
=
;
(2)
+
+
=
;
(3)
+
+
+
+
+
+
=
;
(4)求+
+
+
…+
的整数部分是
| 1 |
| ( ) |
| 1 |
| ( ) |
| 5 |
| 12 |
(2)
| 1 |
| ( ) |
| 1 |
| ( ) |
| 1 |
| ( ) |
| 13 |
| 18 |
(3)
| 1 |
| 2 |
| 1 |
| 6 |
| 1 |
| 12 |
| 1 |
| 20 |
| 1 |
| 30 |
| 1 |
| 42 |
| 1 |
| 56 |
| 7 |
| 8 |
| 7 |
| 8 |
(4)求+
| 10 |
| 100 |
| 10 |
| 101 |
| 10 |
| 102 |
| 10 |
| 110 |
1
1
.分析:(1)把5分解成两个12的因数相加的形式,
(2)把13分解成三个18的因数加相的形式,
(3)把分数拆分为分母为相邻的两个自然数,分子为1的两个分数相减的形式,再计算,
(4)
×11<
+
+
…+
<
×11.
(2)把13分解成三个18的因数加相的形式,
(3)把分数拆分为分母为相邻的两个自然数,分子为1的两个分数相减的形式,再计算,
(4)
| 10 |
| 110 |
| 10 |
| 100 |
| 10 |
| 101 |
| 10 |
| 102 |
| 10 |
| 110 |
| 10 |
| 100 |
解答:解:(1)12的因数有:1,2,3,4,6,12,
因2+3=5,所以
=
+
=
+
,
因1+4=5,所以
=
+
=
+
.
(2)18的因数有:1,2,3,6,9,18,
因13=1+3+9,所以
=
+
+
=
+
+
,
(3)
+
+
+
+
+
+
,
=
+(
-
)+(
-
)+(
-
)+(
-
)+(
-
)+(
-
),
=
+
-
+
-
+
-
+
-
+
-
+
-
,
=1-
,
=
.
(4)
×11<
+
+
…+
<
×11.
1<
+
+
…+
<1.1.
所以它的整数部分是1.
故答案为:6(或12),4(或3),18,6,2,
,1.
因2+3=5,所以
| 5 |
| 12 |
| 2 |
| 12 |
| 3 |
| 12 |
| 1 |
| 6 |
| 1 |
| 4 |
因1+4=5,所以
| 5 |
| 12 |
| 1 |
| 12 |
| 4 |
| 12 |
| 1 |
| 12 |
| 1 |
| 3 |
(2)18的因数有:1,2,3,6,9,18,
因13=1+3+9,所以
| 13 |
| 18 |
| 1 |
| 18 |
| 3 |
| 18 |
| 9 |
| 18 |
| 1 |
| 18 |
| 1 |
| 6 |
| 1 |
| 2 |
(3)
| 1 |
| 2 |
| 1 |
| 6 |
| 1 |
| 12 |
| 1 |
| 20 |
| 1 |
| 30 |
| 1 |
| 42 |
| 1 |
| 56 |
=
| 1 |
| 2 |
| 1 |
| 2 |
| 1 |
| 3 |
| 1 |
| 3 |
| 1 |
| 4 |
| 1 |
| 4 |
| 1 |
| 5 |
| 1 |
| 5 |
| 1 |
| 6 |
| 1 |
| 6 |
| 1 |
| 7 |
| 1 |
| 7 |
| 1 |
| 8 |
=
| 1 |
| 2 |
| 1 |
| 2 |
| 1 |
| 3 |
| 1 |
| 3 |
| 1 |
| 4 |
| 1 |
| 4 |
| 1 |
| 5 |
| 1 |
| 5 |
| 1 |
| 6 |
| 1 |
| 6 |
| 1 |
| 7 |
| 1 |
| 7 |
| 1 |
| 8 |
=1-
| 1 |
| 8 |
=
| 7 |
| 8 |
(4)
| 10 |
| 110 |
| 10 |
| 100 |
| 10 |
| 101 |
| 10 |
| 102 |
| 10 |
| 110 |
| 10 |
| 100 |
1<
| 10 |
| 100 |
| 10 |
| 101 |
| 10 |
| 102 |
| 10 |
| 110 |
所以它的整数部分是1.
故答案为:6(或12),4(或3),18,6,2,
| 7 |
| 8 |
点评:本题主要考查了学生把分数进行拆项来解答问题的能力.
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