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平面曲线与平面曲线之间最小距离

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青青子衿 posted 2013-10-2 13:52 |Read mode
已知曲线$y+x^2+1=0$上有一点P,曲线$x-y^2=0$上有一点$Q$,求$|PQ|$的最小值
貌似要用到偏导数,可是我想应该有初等的方法!!
望高手不吝赐教!

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kuing posted 2013-10-2 14:01
又遇高次方程…………
取最小值时 $P$, $Q$ 处的切线平行且垂直于 $PQ$,列式得到方程组消元后变成五次方程

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其妙 posted 2013-10-2 16:23
回复 1# 青青子衿
偏导数,也是二元三次方程组啊!不好解啊,有软件解么?
original poster 青青子衿 posted 2013-10-2 21:03
回复  青青子衿
偏导数,也是二元三次方程组啊!不好解啊,有软件解么? ...
其妙 发表于 2013-10-2 16:23
试试:
wolframalpha.com

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