9-x²/x²+6x+9÷x²-3x/2x+6-2/x²-x
=-(x+3)(x-3)/(x+3)²×2(x+3)/x(x-3)-2/x(x-1)
=2/x-2/x(x-1)
=(2x-2-2)/x(x-1)
=(2x-4)/x(x-1)
当x=6时
原式=(12-4)/6(6-1)
=4/15