b: 6/x-1=6(x^2+x+1)/(x-1)(x^2+x+1)
2x/x^2+x+1=2x(x-1)/(x^2+x+1)(x-1)
4x^2-3x+5/x^3-1=4x^2-3x+5/(x-1)(x^2+x+1)
a: 8y^2-2x^2=2(2y-x)(2y+x)
7/5x=14(2y-x)(2y+x)/10x(2y-x)(2y+x)
4/x-2y=-40x(2y+x)/10x(2y-x)(2y+x)
x-y/8y^2-2x^2=(x-y)/2(2y-x)(2y+x)=5x(x-y)/10x(2y-x)(2y+x)