1.x^2-2x=99
x^2-2x-99=0
(x-11)(x+9)=0
x=11或x=-9
2.[2x-1]^2+3[2x-1]=0
4x^2-4x+1+6x-3=0
4x^2+2x-2=0
2x^2+x-1=0
(2x-1)(x+1)=0
x=1/2或x=-1