x2-2x+8=0(x-1)2=-7无实数解x2-x-2=4x2-x-6=0(x-3)(x+2)=0x1=3，x2=-2 2x2-3x+1=0(2x-1)(x-1)=0x1=0.5，x2=1不明白可以追问,有用请采纳！
