解方程：
196x平方-1=0
196x^2=1
14x=±1
x1=1/14 x2=-1/14
4x平方+12x+9=81
(2x+3)^2=81
2x+3=±9
x1=3 x2=-6
x平方-7x-1=0
(x-3.5)^2=13.25
x-3.5=±√13.25
x1=3.5+√13.25 x2=3.5-√13.25 .
2x平方+3x=3
x^2+3x/2=3/2
(x+3/4)^2=3/2+9/16=33/16
x+3/4=±√33/4
x1=(√33-3)/4 x2=-(√33+3)/4 .
x平方-2x+1=25
(x-1)^2=25
x-2=土5
x1=7 x2=-3.
x(2x-5)=4x-10
2x^2-5x=4x-10
2x^2-9x+10=0
(2x-5)(x-2)=0
2x-5=0 x1=5/2
x-2=0 x2=2 .
x平方+5x+7=3x+11
x^2+2x=4
(x+1)^2=5
x+1=±√5
x=√5-1 x2=-√5-1 .
1-8x+16x平方=2-8x
16x^2=1
x^2=1/16
x1=1/4 x2=-1/4 .