搜题请搜索小程序“爱下问搜题”
问题 填空题
已知椭圆
x2
25
+
y2
9
上一点P到两焦点距离之积为m，则当m取最大值时，P点坐标______．
答案

设椭圆的左右焦点为F1、F2

根据椭圆的定义，可得|PF1|+|PF2|=2a=10

∵|PF1|•|PF2|≤[

1
2
（|PF1|+|PF2|）]2=25

当且仅当|PF1|=|PF2|=5时，P到两焦点距离之积为m有最大值为25

∴当m取最大值时，P点位于短轴的顶点，其坐标为（0，±4）

故答案为：（0，±4）

多项选择题

下列选项中，属于扩张性的货币政策的主要政策手段的是______。

A．降低利率

B．增加货币供应量

C．提高利率

D．放松信贷控制
查看答案
问答题

In January 2008 Arti entered in a contractual agreement with Bee Ltd to write a study manual for an international accountancy body’s award. The manual was to cover the period from September 2008 till June 2009, and it was a term of the contract that the text be supplied by 30 June 2008 so that it could be printed in time for September. By 30 May, Arti had not yet started on the text and indeed he had written to Bee Ltd stating that he was too busy to write the text.Bee Ltd was extremely perturbed by the news, especially as it had acquired the contract to supply all of the accountancy body’s study manuals and had already entered into extensive preliminary expenses in relation to the publication of the new manual.Required:In the context of the law of contract, advise Bee Ltd whether they can take any action against Arti. (10 marks)
查看答案