设AB:Y=10-2X
则设P(X,10-2X),|PA|^2=(X-1)^2+(10-2X-8)^2,
|PB|^2=(X-5)^2+(10-2X)^2
因为|PA|=3|PB|,所以|PA|^2=9|PB|^2
连立方程组得X=4或7所以P(4,2)或(7,-4)
设AB:Y=10-2X
则设P(X,10-2X),|PA|^2=(X-1)^2+(10-2X-8)^2,
|PB|^2=(X-5)^2+(10-2X)^2
因为|PA|=3|PB|,所以|PA|^2=9|PB|^2
连立方程组得X=4或7所以P(4,2)或(7,-4)