[(x^2+4)/(x -4)]/[(x^2-4)/(x^2+2x)]=[(x^2+4)/(x -4)]*(x^2+2x)/(x^2-4)=[(x^2+4)/(x -4)]*x(x+2)/[(x-2)(x+2)]=[(x^2+4)/(x -4)]*x/(x-2)=x(x^2+4)/[(x -4)(x-2)]=x(x^2+4)/(x^2-6x+8)
