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问题 解答题

运用平方差，完全平方公式解方程：

（1）16（x-1）2=225

（2）4x2-4x+1=x2-6x+9

（3）9（x+1）2=4（x-1）2

（4）x2-4x+4=（3-2x）2

答案

（1）16（x-1）2-152=0，

所以[4（x-1）+15][4（x-1）-15]=0，

即4x+11=0，4x-19=0，

得x1=-

11
4
，x2=
19
4
．

（2）方程变为（2x-1）2-（x-3）2=0，

所以[（2x-1）+（x-3）][（2x-1）-（x-3）]=0，

即3x-4=0，x+2=0，

得x1=

4
3
，x2=-2．

（3）原方程变为[3（x+1）]2-[2（x-1）]2=0，

所以[3（x+1）+2（x-1）][3（x+1）-2（x-1）]=0，

即（5x+1）（x+5）=0，

得x1=-

1
5
，x2=-5．

（4）（x-2）2=（3-2x）2．

（x-2）2-（3-2x）2=0，

（x-2+3-2x）（x-2-3+2x）=0，

（1-x）（3x-5）=0，

所以x1=1，x2=

5
3
．

单项选择题

Visitors to this country are normally admitted for six months, but foreign students can usually stay for one year. They must (54) an educational institution, and they are required to study for a (55) of fifteen hours a week on a daytime course. Prospective students have to show that they can afford their studies, and that they have sufficient (56) resources to support themselves (57) in this country.

In order to work here the foreigner needs a work permit, (58) must be applied for by his prospective employer. The problem here is that the Department of Employment has the right to grant or (59) these permits, and there is little that can be done (60) it; it would be extremely unwise for a foreign visitor to work (61) a permit, since anyone doing so is liable to immediate deportation (驱逐出境). There are some people from the European countries, who are often given (62) residence permits of up to five years. Some other people, such as doctors, foreign journalists, authors and others can work without permits, and foreign students are normally allowed to (63) part-time jobs while they are studying here.

55().

A.minimum 

B.maximum 

C.minority 

D.majority
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选择题

我市的小麦种植很普遍，在小麦开花时节，如果阴雨连绵，小麦会出现籽粒空瘪现象，导致减产．其主要原因是（　　）

A．光照不足缺少营养

B．下雨影响传粉

C．阴雨天气病虫害多

D．下雨影响开花
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