x-1分之2-x＞3
(x-1分之2)-x-3＞0
[2-(x+3)(x-1)] / (x-1)>0
(-x^2 -2x +5)/ (x-1)>0
[-(x+1)^2 +6 ] (x-1)>0
[(x+1)^2 - 6 ] (x-1)