解方程1/(x+3)+2/(3-x)=12/x^2-9

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解方程1/(x+3)+2/(3-x)=12/x^2-9
解方程1/(x+3)+2/(3-x)=12/x^2-9

解方程1/(x+3)+2/(3-x)=12/x^2-9
1/(x+3)+2/(3-x)=12/(x^2-9)
1/(x+3) -2/(x-3)=12/(x-3)(x+3)
两边同时乘以(x-3)(x+3)得
(x-3) -2(x+3)=12
x-3-2x-6=12
x=-21
经检验x=-21是方程的解

1/(x+3)+2/(3-x)=12/x^2-9
(x-3)/(x^2-9) + 2(x+3)/(x^2-9) =12/x^2-9
两边同时乘以(x^2-9),得
x-3+2x-6=12
3x=21
x=7