3x/(1-3x)(1+3x)=1/2-x/2(3x-1)
3x=1/2(1-3x)(1+3x)+x(1+3x)/2
6x=(1-3x)(1+3x)+x(1+3x)
6x=1-9x^2+1x+3x^2
6x^2+5x-1=0
(6x-1)(x+1)=0
x=1/6 -1