题干

已知函数f(x)=loga(1﹣x)+loga(x+3)(0<a<1)

(1)求函数f(x)的定义域;

(2)求函数f(x)的零点;

(3)若函数f(x)的最小值为﹣4,求a的值.

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答案(点此获取答案解析)

解:(1)要使函数有意义:则有1-x>0x+3>0

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阅读理解

“Chicken” idioms(习语)

    The word “chicken” is used in so many English idioms. Do you know the following?

    Don't count your chickens before they hatch.

    The expression“Don't count your chickens before they hatch”means “Don't expect that all your eggs, which have been laid, will hatch. “Hatch” is a verb, meaning the baby chicken breaks open the shell of the egg and comes out successfully. So the expression mainly means “Don't depend on things working out just as you want them to.” this saying appears in the story The Milkmaid and Her Pail in Aesop's Fables.

    A chicken-and-egg situation

    In history, philosophers(哲学家)and scientists have met this dilemma(困境): Which came first, the chicken or the egg? Aristotle thought that both the bird and the egg must have always been there. However, more recently, scientists such as Stephen Hawking have argued that the egg came before the chicken. In common speech, the term “a chicken-and-egg situation” means a situation where it is impossible to say which of two things appeared first and which caused the other one.

    Don't be such a chicken

    There seems to be an idea in English, somehow, that a chicken is a scared bird. Maybe that's not fair as most birds will probably fly away from you if you go towards them. But “Don't be such a chicken” means “Don't be so scared and get a bit more courage.” So if your friend fear to do something, you can say to him or her, “Don't be such a chicken. Just have a try!”