过两点（u,2t）,（t-2,u）的直线l的斜率为2即:(u-2t)/(t-2-u)=2u-2t=2t-4-2u3u=4t-4u=(4t-4)/3设直线方程是:y-2t=2(x-u)即:y=2x-2u+2t在Y轴上的截距是m=-2u+2t=-2(4t-4)/3+2t=-8t/3+8/3+2t=-2t/3+8/3因为:1...