幫幫手﹏PLZ

x^2-2x=0
x^2-2x+1^2-1^2=0
x^2-2x+1=1
(x-1)^2=1
x-1=-1 or x-1=1
x=0 or x=2//

x^2-4x+1=0
x^2-4x+2^2-2^2=-1
x^2-4x+4=3
(x-2)^2=3
(x-2)=-√3 and (x-2)=√3
x=-2-√3 and √3+2//

2x^2 +6x = 1
x^2+3x=1/2
x^2+3x+(3/2)^2-(3/2)^2=1/2
(x+3/2)^2=11/4
x+3/2=√11/2 and x+3/2=-√11/2
x=(√11-3)/2 and (-√11-3)/2//

-x^2-3x =5
x^2+3x=-5
x^2+3x-(3/2)^2+(3/2)^2=-5
(x+3/2)^2=-11/4
(no root)