1.(x-√5/5)(x+√5/5)=0 x=±√5/52.4x^2=0 x=03.(2x-a)(x-a)=0 x=a/2 ,a4.[x+(a+2)][x+(a+2)]=0 x=-a-2 , 2-a5.3(x-1)^2=4 x=1+(2√3)/3 , 1-(2√3)/36.万能公式法 x=(3+√17)/4 ,(3-√17)/4希望能帮到你