设动点坐标为 P(x,y)则 √[(x-1)²+(y-2)²]=|5x-y-3|/√(5²+1²)=> (x-1)²+(y-2)²=(5x-y-3)²/26=> 26x²-52x+26+26y²-104y+104=25x²+y²+9-10xy-30x+6y=> x...