4-4x+x^2分之2x^2-8除以[2(x+3)*x^2-9分之3-x]
=2(x+2)(x-2)/(x-2)^2÷[-2(x+3)*(x-3)/(x+3)(x-3)]
=2(x+2)/(x-2)÷(-2)
=-(x+2)/(x-2)