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函数题是SAT数学考试中常考题型，下面我们为大家详细解析一下函数题如何解，大家可以借鉴一下思路。希望对大家的备考有所帮助。

If f(x) = x2 – 3, where x is an integer, which of the following could be a value of f(x)?

　　I 6　　II 0　　III -6

　　A. I only

　　B. I and II only

　　C. II and III only

　　D. I and III only

　　E. I, II and III

Correct Answer: A

解析:

Choice I is correct because f(x) = 6 when x=3. Choice II is incorrect because to make f(x) = 0, x2 would have to be 3. But 3 is not the square of an integer. Choice III is incorrect because to make f(x) = 0, x2 would have to be –3 but squares cannot be negative. (The minimum value for x2 is zero; hence, the minimum value for f(x) = -3)

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