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待定系数法是初中数学中的一种常用的解题方法,这里举例说明待定系数法的应用.一、用待定系数法求方程(组)中待定系数的值例1(2013年扬州中考题)已知关于x的方程3x+n2x+1=2的解是负数,则n的取值范围为.分析求出分式方程的解x=n-2,得出n-2<0,求出n的范围,根据分式方程得出n-2≠-12,求出n,即可得出答案.本题关键是得出n-2<0和n-2≠-12,注意题目中的隐含条件2x+1≠0,不要忽略.
To be determined coefficient method is a commonly used in junior high school mathematics problem-solving method, an example of the application of undetermined coefficient method.First, with undetermined coefficient method to determine the equation (group) to be determined coefficient value Example 1 (Yangzhou 2013 senior high school entrance examination questions) Knowing that the solution to equation 3x + n2x + 1 = 2 for x is negative, then the range of n is 0. Analyzing the solution to a fractional equation x = n-2 yields n-2 <0, n range, according to the fractional equation derived n-2 ≠ -12, find n, you can come to the answer. The key is to get n-2 <0 and n-2 ≠ -12, pay attention to the problem of hidden Containing the conditions 2x + 1 ≠ 0, do not ignore.