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研究发现,经过抛物线y=ax2上两点的直线方程,结构优美,应用广泛.为叙述方便,本文中约定:点P的横坐标记为xP,经过A、B两点的直线的方程记为lAB,直线AB的斜率记为kAB,直线AB在y轴上的截距记为bAB,抛物线y=ax2上点A处的切线记为lAA,抛物线y=ax2上点A处的切线的斜率记为kAA.定理设A,B是抛物线y=ax2上的两点,则lAB:y=a(xA+xB)x-axA xB,kAB=a(xA+xB),bAB=-axA xB.
The study found that, after the parabola y = ax2 two points on the straight line equation, the structure of a beautiful, widely used.To facilitate the narrative, the paper agreed: point P abscissa marked xP, A, B after two points of the equation was lAB, the slope of the straight line AB is recorded as kAB, the intercept of the straight line AB on the y axis is denoted as bAB, the tangent line at point A on y = ax2 is denoted as lAA, and the slope of the tangent line at point A on ax2 = Is kAA. Theorem Let A and B be two points on the parabola y = ax2, then lAB: y = a (xA + xB) x-axA xB, kAB = a (xA + xB) and bAB = -axA xB.