1.x+1/(3-x)>0
(3x-x^2+1)/(3-x)>0
(x^2-3x+1)/(x-3)>0
(x^2-3x+1)(x-3)>0
[x+(3+5^(1/2))/2][x-(3+5^(1/2))/2](x-3)>0
x>3或-(3+5^(1/2))/2