经调查研究，某工厂生产的一种产品的总利润y（元）与销售价格x（元／件）的关系式为y=-4x2+1360x-93200，其中100≤x＜245，
（1）销售价格x是为多少元时，可以使总利润达到22400元？
（2）总利润可不可能达到22500元？
解：（1）由题意，把y=22400代入
，
得
，
原方程可以写成：
，
解得
。
（2）把y=22500代入
，
得，
∵a=1，b=-340，c=28925，
∴b2-4ac=（-340）2-4×1×28925=-100<0，
∴方程没有实数根，
故总利润可不可能达到22500元。
Once a man came to a wise man’s house and said, “I have many bad habits. Which one of them should I give up first?” The wise man said, “Never tell lies and always speak the truth.” The man 36 to do so and went home. At night, the man was about to go out to steal. Before 37 , he 38 for a moment about the promise he made to the wise man. “If he asks me where I have been, what shall I say? Shall I say I went out stealing? No, I can’t say that. But nor can I lie. If I tell the truth, everyone will start 39 me and call me a thief. I would be 40 for stealing.” So the man decided not to steal that night, and gave up this bad habit. Next day, he wanted to drink wine. He was 41 to do so when an idea stopped him. “What shall I say to the wise man if he asks me what I did during the day? I can’t tell a lie.” And so he dropped the idea of drinking wine. 42 , whenever the man thought of doing something bad, he remembered his promise to tell the truth 43 . One by one, he gave up all his bad habits and became a very good person. Telling the truth is a very good habit. If you always speak the truth, you can 44 yourself from a lot of trouble and become a person everyone likes and favors. Make a promise: I 45 always speak the truth.
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