研究函数问题 ,通常要透视函数的本质特征 .反比例函数 y =kx(k为非零常数 )的本质特征是“变量y与x的乘积是一个常数k” .由此可以得到反比例函数的两个重要结论 :若A点是反比例函数y=kx(k≠ 0 ) 图象上的任意一点 ,且AB垂直于x轴 ,AC垂直于y轴 ,垂足分别是点B、C(如图 1所示 To study function problems, it is usually necessary to look at the essential features of the function. The essential feature of the inverse-proportional function y = kx (k is a non-zero constant) is that “the product of the variable y and x is a constant k.” Thus, two of the inverse proportional functions can be obtained. Important conclusions: If point A is an arbitrary point on the image of the inverse proportional function y=kx(k≠ 0), and AB is perpendicular to the x axis, AC is perpendicular to the y axis, and the perpendicular feet are points B and C (as shown in Figure 1). Show