分式的加减：(x-3/x²+6x+9)+(x/9-x²)

分式的加减：(x-3/x²+6x+9)+(x/9-x²)
分式的加减：(x-3/x²+6x+9)+(x/9-x²)

分式的加减：(x-3/x²+6x+9)+(x/9-x²)
(x-3)／(x+3)^2+x／(3+x)(3-x)
=[(x-3)^2-x(x+3)]／(x+3)^2(x-3)
=(x^2-6x+9-x^2-3x)／(x+3)^2(x-3)
=(-9x+9)／(x+3)^2(x-3)
=9(1-x)／(x+3)^2(x-3)

原式=(x-3)/(x+3)²-x/(x+3)(x-3)
=[(x-3)²-x(x+3)]/(x+3)²(x-3)
=(x²-6x+9-x²-3x)/(x+3)²(x-3)
=(x²-6x+9-x²-3x)/(x+3)²(x-3)
=(9-9x)/(x+3)²(x-3)