(1)3x/(x+2)>x+6;(2)x+1+5x^2/(x+2)≥1/(1-x);
(3)在数轴上,点A=1,B=-2,P=k,若|PA|=5,则k=____,若|PA|+|PB|=5,则k=____,若|PA|+|PB|