2x^2-x-3=(2x-3)(x+1)>=0
>>>x>=3/2 or x<=-1详细步骤2x^2-x-3=(2x-3)(x+1)>=0,2x-3>=0,and x+1>=0,>>>x>=3/2 or2x-3<=0,and x+1<=0 >>>x<=-1