1/(6x-4y)+1/(6x+4y)-3x/(4y^2-9x^2)=1/[2*(3x-2y)]+1/[2*(3x+2y)]+3x/(9x^2-4y^2)=1/[2*(3x-2y)]+1/[2*(3x+2y)]+3x/[(3x+2y)*(3x-2y)]=[(3x+2y)+(3x-2y)+6x]/2*[(3x+2y)*(3x-2y)]=6x/[(3x+2y)*(3x-2y)]