即x^2 - 2 * x - 3 < 0(x - 3) * (x + 1) < 0则 -1 < x < 3
-x2+2x+3>0x2-2x-3<0(x-3)(x+1)<0-1
-(x²-2x-3)>0-(x-3)(x+1)>0(x-3)(x+1)<0-1
-x²+2x+3>0x²-2x-3=(x-3)(x+1)<0-1
