摘要: 词数:120左右.要用定语从句.连词 though , not only -but also -, so -that, whenever , -ing , 感叹句. 形容词. 强调句等. (并在你写的作文中将以上用到的词或句型下画线) -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
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如图,椭圆
+
=1的两焦点F1,F2与短轴两端点B1,B2构成∠B2F1B1为120°,面积为2
的菱形.
(1)求椭圆的方程;
(2)若直线l:y=kx+m与椭圆相交于M,N两点(M,N不是左右顶点),且以MN为直径的圆过椭圆右顶点A,求证:直线l过定点,并求出该定点的坐标.
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| x2 |
| a2 |
| y2 |
| b2 |
| 3 |
(1)求椭圆的方程;
(2)若直线l:y=kx+m与椭圆相交于M,N两点(M,N不是左右顶点),且以MN为直径的圆过椭圆右顶点A,求证:直线l过定点,并求出该定点的坐标.
下面的三角形数阵叫“莱布尼兹调和三角形”,它们是由整数的倒数组成的,第n行有n个数且两端的数均为
(n≥2),每个数是它下一行左右相邻两数的和,如
=
+
,
=
+
,
=
+
,…,则第10行第3个数(从左往右数)为
.
…
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| 1 |
| n |
| 1 |
| 1 |
| 1 |
| 2 |
| 1 |
| 2 |
| 1 |
| 2 |
| 1 |
| 3 |
| 1 |
| 6 |
| 1 |
| 3 |
| 1 |
| 4 |
| 1 |
| 12 |
| 1 |
| 360 |
| 1 |
| 360 |
| 1 |
| 1 |
| 1 |
| 2 |
| 1 |
| 2 |
| 1 |
| 3 |
| 1 |
| 6 |
| 1 |
| 3 |
| 1 |
| 4 |
| 1 |
| 12 |
| 1 |
| 12 |
| 1 |
| 4 |
| 1 |
| 5 |
| 1 |
| 20 |
| 1 |
| 30 |
| 1 |
| 20 |
| 1 |
| 5 |
…