题目内容
![](http://thumb.1010pic.com/pic3/upload/images/201206/57/529d4942.png)
1 |
x |
n-1 |
2n |
n-1 |
2n |
分析:先确定M1(1,1),M2(2,
),M3(3,
),…,Mn(n,
),再根据三角形面积公式得到S△P1M1M2=
×1×(1-
),S△P2M2M3=
×1×(
-
),…,S△Pn-1Mn-1Mn=
×1×(
-
),然后把它们相加即可.
1 |
2 |
1 |
3 |
1 |
n |
1 |
2 |
1 |
2 |
1 |
2 |
1 |
2 |
1 |
3 |
1 |
2 |
1 |
n-1 |
1 |
n |
解答:解:∵M1(1,1),M2(2,
),M3(3,
),…,Mn(n,
),
∴S△P1M1M2=
×1×(1-
),S△P2M2M3=
×1×(
-
),…,S△Pn-1Mn-1Mn=
×1×(
-
),
∴S△P1M1M2+S△P2M2M3+…+S△Pn-1Mn-1MN=
×1×(1-
)+
×1×(
-
)+…+
×1×(
-
)
=
(1-
+
-
+…+
-
)
=
•
=
.
故答案为
.
1 |
2 |
1 |
3 |
1 |
n |
∴S△P1M1M2=
1 |
2 |
1 |
2 |
1 |
2 |
1 |
2 |
1 |
3 |
1 |
2 |
1 |
n-1 |
1 |
n |
∴S△P1M1M2+S△P2M2M3+…+S△Pn-1Mn-1MN=
1 |
2 |
1 |
2 |
1 |
2 |
1 |
2 |
1 |
3 |
1 |
2 |
1 |
n-1 |
1 |
n |
=
1 |
2 |
1 |
2 |
1 |
2 |
1 |
3 |
1 |
n-1 |
1 |
n |
=
1 |
2 |
n-1 |
n |
=
n-1 |
2n |
故答案为
n-1 |
2n |
点评:本题考查了反比例函数y=
(k≠0)中比例系数k的几何意义:过反比例函数图象上任意一点分别作x轴、y轴的垂线,则垂线与坐标轴所围成的矩形的面积为|k|.
k |
x |
![](http://thumb2018.1010pic.com/images/loading.gif)
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