正比例函数y=±x图象关于原点中心对称.直线y=x是一、三象限的角平分线,直线y=-x是二、四象限的角平分线.解有关直线y=±x与其他函数图象有交点的问题时,若能利用直线y=±x的有关性质,则能使问题迎刃而解.一、利用直线y=x上的点与原点的连线段、点与坐标轴的垂线段和一坐标轴围成等腰直角三角形例1如图1,已知直线y=x与二次函数y=x2+bx+c的 Proportional function y = ± x The image is symmetric with respect to the origin. Line y = x is the angle bisector of one and three quadrants, and line y = -x is the bisector of the quadrant. Solutions about the line y = ± x and Other functions have the intersection of the problem, if we can use the relevant properties of the line y = ± x, you can solve the problem.First, the use of straight line y = x point and the origin of the connection segment, the point and the axis Vertical line segment and a coordinate axis enclosed isosceles right triangle Example 1 As shown in Figure 1, known linear y = x and quadratic function y = x2 + bx + c