一、观察法通过观察,获取直接或间接信息,从而找出正确答案的方法称为观察法.观察法主要用于选择具有某些特殊规律或具有可比性的问题.例1方程(k-1)x~2-(1-kx)~(1/2)+1/4=0有两个实数根,则k的取值范围是().A.k≥1 B.k≤1 C.k>1 D.k<1解析:观察可知,原方程有两个实数根,故原方程为二次方程,二次 First, the observation method Through observation, access to direct or indirect information to find the correct answer is called the observation method. Observation method is mainly used to select some special laws or comparable problems .Example 1 (k-1 ) x ~ 2- (1-kx) ~ (1/2) + 1/4 = 0 has two real roots, then the range of k is () .Ak≥1Bk≤1Ck> 1Dk <1 Analysis: Observations show that the original equation has two real roots, so the original equation quadratic equation, twice