1/(x+3)-2/(3-x)=12/(x²-9)
1/(x+3)+2/(x-3)=12/(x²-9)
[(x-3)/((x+3)(x-3)]+[2(x+3)/(x+3)(x-3)]=12/(x²-9)
(x-3)/(x²-9)+2(x+3)/(x²-9)=12/(x²-9)
[(x-3)+2(x+3)]/(x²-9)=12/(x²-9)
x-3+2x+6=12
3x+3=12
3x=12-3
x=3
经检验
x=3是原方程的增根
所以原方程无解.