1。左边≥0,只需要右边<0,就无解,则1-k12.△=0,即4k^2-4(2-k)=0,k=-2,1,带入,x^2-2x+1=0,x1=x2=13.△=0,即(k+2)^2-16(k-1)=0,k=2,10,带入,4x^2-4x+1=0,x1=x2=1/2或者,4x^2-12x+9=0,x1=x2=3/24.不等根,△>0,即(k+2)^2-(k^2-4)>0,k>-2,等根△=0,即(k+2)^2-(k^2-4)=0,k=-2,无实根,△<0,即(k+2)^2-(k^2-4)<0,k<-2,5..△=16t^4-4(t^2+4)(t^2+1)=12t^4-20t^2-16=4(3t^4- |