解：设P点坐标为(x,y) 则有：AP=(x+3,y-2), PB=(4-x,-8-y)因：AP=3BP所以有：x+3=3(4-x) 解得：x=9/4y-2=3(-8-y) 解得：y=-11/2所以点P为(9/4,-11/2)
Px=4-1/3*[4-(-3)]=5/3Py=4-1/3*[-8-2]=22/3
