原式=[x^2/4x(x-1)]*[2(x+1)/x^3]-[x(x+2)/3(x+1)(x-1)]*[(x+1)/x]
=(x+1)/2x^2(x-1)-(x+2)/3(x-1)
=(3x+3-2x^3-4x^2)/6x^2(x-1)
=-(x-1)(2x^2+6x+3)/6x^2(x-1)
=-(2x^2+6x+3)/6x^2
原式=[(x^2-4)/x]/[(x^2-5x+6)/x]
=(x+2)(x-2)/(x-2)(x-3)
=(x+2)/(x-3)
=(7/4+2)/(7/4-3)
=-3