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问题 填空题
已知a＞0，b＞0，a+b=1，则
1
a
+
1
b
的取值范是______．
答案

∵a＞0，b＞0，a+b=1，∴

1
a
+
1
b
=(a+b)(
1
a
+
1
b
)=2+
b
a
+
a
b
≥2+2
b
a
×
a
b
=4，当且仅当a=b=
1
2
时取等号．

∴

1
a
+
1
b
的取值范围是[4，+∞）．

故答案为[4，+∞）．

阅读理解
Most visited museums in the world

The British Museum, London, UK
It is one of the world’s greatest museums of human history and culture. It was opened on Jan 15, 1759. And now it has about 8 million things, from the stone tools of early men to 20th century inventions. Some famous inventions are on show there, such as the bicycle, the telephone, the television and so on.

Musee du Louvre, Paris, France
It was first built in 1204, but as a museum, it was opened in 1793. Once a palace that was homes to kings of France, the Louvre is now the world’s most famous museums. Millions of visitors go to the museum every year. It’s famous for some of the best pieces of art in the world.

The Metropolitan Museum of Art, New York, US
The museum is one of the world’s largest museums. It was opened in 1872.  There are over 2 million things of art. You can see many interesting things from Africa and the Middle East. Of course, it has a great collection of American art. If you are interested in American history, don’t miss it.
小题1:How many things are there in the British Museum now ?
A．2 million B．8 millionC． 5 million D．7 million
小题2:When was Musee du Louvre opened as a museum?
A．1759B．1204C．1793D．1872
小题3:In the passage, we know the Metropolitan Museum of Art is __________.
A．in New YorkB．once a palace C．not interestingD．famous for science
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填空题

写出满足下列条件的一元一次方程①未知数系数是3，②方程的解是-3，这样的方程可以是                
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