x-3分之x-x的平方-3x分之x+6+x分之1
=x/(x-3)-(x+6)/x(x-3)+1/x
=(x²-x-6+x-3)/x(x-3)
=(x²-9)/x(x-3)
=(x+3)(x-3)/x(x-3)
=(x+3)/x
=x分之（x+3)