2x－7y＋8＝02x=7y-8x=7y/2-4则有(7y/2-4-5)^2+(y+1)^2=(7y/2-4-0)^2+(y-4)^2(7y/2-9)^2- (7y/2-4)^2=(y-4)^2-(y+1)^2(7y-13)*(-5)=(2y-3)(-5)7y-13=2y-35y=10y=2x=7*2/2-4=3r^2=(3-5)^2+(2+1)^2=4+9=13所以圆方程为...