Under the first radical sign, it can be transformed into (X-4) square +(Y-2) square. This semi-formula represents the distance from P(X, y) to (4,2), and the second root sign can also be changed to (X-0) square +(Y- 1) square, and this semi-formula represents the distance from P(X, y) to (0, 1). Then combine the numbers with the shapes. Make a straight line x+y+3=0. Then mark (4,2) and (0, 1), because the distance brought by the three-point * * line is the shortest, so the focal coordinate connecting these two points and the straight line x+y+3=0 is the P point, so XY is known, and then it can be solved by bringing it into the formula.