x=x分之1
x^2=1
x-3分之x方-6x=9处以x方+6x+9分之x+3
=(x^2-6x+9/x-3) ÷（x+3/x^2+6x+9)
=(x-3)^2/(x-3) ÷（x+3)/(x+3)^2
=(x-3) ×(x+3)
=x^2-9
=1-9
=-8