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将一次函数、二次函数、反比例函数融合在同一问题中,构成综合型试题,是近几年中考中的热点考题.本文从近几年的中考题中撷取数例略加解析,供参考.一、寻找函数例1下列函数中,当x>0时,y随x的增大而减小的是()(A)y=2x(B)y=1/3x-1(C)y=-2/x(D)y=-2x~2分析根据正比例函数,一次函数,反比例函数以及二次函数的增减性对各选项分析判断后,利用排除法求解.解(A)k=2>0,y随x增大而增大,故此选项错误;
The first function, quadratic function and inverse function are integrated in the same question to form a comprehensive test, which is a hot topic in the middle school entrance examination in recent years. First, look for the function example 1 In the following function, when x> 0, y decreases with the increase of x () (A) y = 2x (B) y = 1 / 3x-1 = -2 / x (D) y = -2x ~ 2 Analysis After analyzing and judging each option according to the positive and negative functions, the inverse function and the addition and subtraction of the quadratic function, 2> 0, y increases with x increases, so the option is wrong;