x^2-2x-3>0x^2-3x+x-3>0x(x-3)+(x-3)>0(x-3)(x+1)>0两个括号相乘大于0则两个都大于0或都小于0则x-3>0,x+1>0,则x>3或x-3<0,x+1<0,则x<-1所以x>3或x<-1
