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一元二次方程问题是中考的一个必考内容,也是命题者设计“陷阱”的热点,为了帮助同学们学习时就避开“陷阱”,现举例剖析. 一、利用方程有解的含义设计“陷阱” 例1(1998年盐城市中考题)如果关于x的方程(m-2)x2-2x+1=0有解,那么m的取值范围是( ).(A)m<3 (B)m≤3(C)m<3且m≠2 (D)m≤3且m≠2误解由题意,知解之,得 ,故选(D). 剖析由于题设中对m和方程的次数未作任何规定.因此原题可理解为“一元二次方
One-member quadratic equation is an important part of the examination and is also a hot spot for propositioners to design “traps.” To help students avoid “traps” when they are learning, an example is presented. First, use the meaning of equations to solve the design. Trap Example 1 (1998 Yancheng Exam Questions) If there is a solution to the equation (m-2) x2-2x+1=0 for x, then the range of m is (). (A)m<3 (B ) m ≤ 3 (C) m <3 and m ≠ 2 (D) m ≤ 3 and m ≠ 2 misunderstood by the meaning of the problem, knowing the solution, getting, choosing (D). Analysis of the problem due to the middle of the equation m There is no provision for the number of times, so the original question can be understood as