2. the image of parabola y=ax2+bx+c(a≠0): when a >; 0, the opening is upward, when a; 0, when x ≤-b/2a, y decreases with the increase of x; When x ≥-b/2a, y increases with the increase of X. If a; 0, the image and the X axis intersect at two points A(x 1, 0) and B(x2, 0), where x 1 and x2 are two roots of the unary quadratic equation ax2+bx+c=0 (a≠0). The distance between these two points is AB = | X2-X65438. When delta < 0. The image does not intersect with the x axis. When a >; 0, the image falls above the X axis, and when X is an arbitrary real number, there is y >；; 0; When a<0, the image falls below the X axis, and when X is an arbitrary real number, there is Y.