数学题x-15/x^2-9-2x/9-x^2÷x/3+x

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数学题x-15/x^2-9-2x/9-x^2÷x/3+x
数学题x-15/x^2-9-2x/9-x^2÷x/3+x

数学题x-15/x^2-9-2x/9-x^2÷x/3+x
原式=[ (x-15)/(x²-9) ]- [ 2x/(9-x²) ]÷[ x/(3+x) ]
=[ (x-15)/(x²-9) ]+[ 2x/(x²-9) ]×[ (x+3)/x ]
=[ (x-15)/(x²-9)] +[ 2(x+3)/(x²-9) ]
=[ (x-15)+2(x+3) ]/(x²-9)
=(x-15+2x+6)/(x²-9)
=(3x-9)/(x²-9)
=3(x-3)/[(x-3)(x+3)]
=3/(x+3)

(x-15)/(x^2-9)-2x/(9-x^2)÷x/(3+x)
=(x-15)/(x^2-9)-2x/(9-x^2)×(3+x)/x
=(x-15)/(x^2-9)+2(x+3)/(x^2-9)
=(x-15+2x+6)/(x+3)(x-3)
=(3x-9)/(x+3)(x-3)
=3/(x+3)