设实数a、b、c满足
|
证明：将
=|
+1 a2
+1 b2 1 c2
+1 a
+1 b
|两边平方，得1 c
+1 a2
+1 b2
=1 c2
+1 a2
+1 b2
+2（1 c2
+1 ab
+1 bc
）1 ac
整理，得a+b+c=0，
又当x=1时，y=ax2+bx+c=a+b+c=0，
∴抛物线y=ax2+bx+c通过定点（1，0）．
| 完形填空 | ||||
| One famous artist Sheikh went back to his hometown. He hadn't seen one of his friends for many years, who was a __1__and needy man. When Sheikh asked about him, he was told by people that the man he was__2__was a rich man and no longer poor. Sheikh__3__to pay a visit to his friend. __4__talking with his friend, Sheikh asked him the __5__for the change in his situation. The man replied that he had been so poor that he was forced to__6__some properties(财产)that belonged to him, like furniture(家具). By selling these things, he had__7__some money enough to start a __8__ with. As he was on his way back to his house with the__9__, he saw a poor lady__10__by the road. The man asked the lady the reason, and she__11__that her husband died and her children were__12__. Hearing this, the man felt__13__for her, and on seeing that she__14__the money more than himself, he gave all the money to her. He__15__home and spent the night, sad and__16__for his family. The next morning, __32__he was summoned(召唤) to the house of a rich man. He was told by the rich man that he had six thousand bags of__33__which he wanted to sell quickly and the man could buy it at a__34__price on loan(借用) from him. The poor man did so and sold the rice__35__. He took some more bags several days later and in this way he was able to make much more money. Soon he became rich. | ||||
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