1
(9x^2+3x)/(x+3)^2* (x^2-3x+9)(x+3)/x(x-3)*(x^2-9)/(x^2-3x+9)
=3x
2
3
=(x-1)(x+3)^2/(x-1)(x+3)(x-4)
=x+3/(x-4)
4
(x^2 +1)/x =3
x+1/x=3
liang bian ping fang
x^2+1/x^2=9-2=7
liang bian ping fang
x^4+1/x^4=49-2=47
x^3 + 1/x^3=(x^2+1/x^2-1)(x+1/x)=18
gu yuan shi=50/50=1