（x+6)²-9=0
(x+6)^2=9
x+6=±3
x=-3或-9
x^2-2x+1=25
(x-1)^2=25
x-1=±5
x=6或x=-4
4x^2+12x+9=81
(2x+3)^2=81
2x+3=±9
x=3或x=-6
3x^2+5(2x+1)=0
3x^2+10x+5=0
x=(-10±√(10^2-4*3*3))/2*3=(-5±√10)/3
3(x-5)^2=2(x-5)
(x-5)(3x-15-2)=0
(x-5)(3x-17)=0
x=5或x=17/3
x(2x-5)=4x-10
x(2x-5)-2(2x-5)=0
(2x-5)(x-2)=0
x=5/2或x=2