如何算极限lim{(9-x^2)/(x^2-4x+3)},

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如何算极限lim{(9-x^2)/(x^2-4x+3)},
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如何算极限lim{(9-x^2)/(x^2-4x+3)},
如何算极限lim{(9-x^2)/(x^2-4x+3)},

如何算极限lim{(9-x^2)/(x^2-4x+3)},
原式=lim{-[(x+3)(x-3)]/[(x-1)(x-3)] x→3
=lim{-(x+3)/(x-1)} x→3
=-(3+3)/(3-1)
=-3

分母可以因式分解为(x-1)(x-3),分子分解为(3-x)(3+x),相消,结果是-3