F(xï¼yï¼z)=aâx+bây+câz-1;(aãbãc>0ï¼xãyãzâ§0)
∂F/∂x=a/2âxï¼∂F/∂y=b/2âyï¼∂F/∂z=c/2âzï¼
设M(x₁ï¼y₁ï¼z₁)æ¯æ²é¢Fä¸çä»»æä¸ç¹ï¼é£ä¹è¿Mçåå¹³é¢æ¹ç¨ä¸ºï¼
[a/2âx₁](x-x₁)+[b/2ây₁](y-y₁)+[c/2âz₁)(z-z₁)=0
å³[a/2âx₁]x+[b/2ây₁]y+[c/2âz₁)-(1/2)(aâx₁+bây₁+câz₁)=0
å°aâx₁+bây₁+câz₁=1代å
¥å¾åé¢æ¹ç¨ä¸ºï¼[a/2âx₁]x+[b/2ây₁]y+[c/2âz₁)-(1/2)
åç®å¾(a/âx₁)x+(b/ây₁)y+(c/âz₁)z-1=0...........â
令z=0ï¼å¾åé¢ä¸xoyåæ å¹³é¢ç交线æ¹ç¨ä¸ºï¼(a/âx₁)x+(b/ây₁)y=1
æ¤äº¤çº¿ä¸oxï¼oyè½´ç交ç¹åæ åå«ä¸ºï¼A((âx₁)/aï¼0ï¼0)ï¼B(0ï¼ây₁)/bï¼0);
ç±OABæç»æçä¸è§å½¢çé¢ç§¯S=(âx₁y₁)/(2ab)ï¼
å令â ä¸çx=0ï¼y=0ï¼å³å¾åé¢æä¸åæ å¹³é¢æå´æçé¥ä½çé«h=(âz₁)/c;
æ
é¥ä½çä½ç§¯V=(âx₁y₁z₁)/(6abc)ï¼å½x₁=y₁=z₁=1/(a+b+c)²æ¶ï¼ä½ç§¯Vè·å¾æ大å¼ï¼
Vmax=[1/(a+b+c)³]/(6abc)=1/[6abc(a+b+c)³]
温馨提示:答案为网友推荐,仅供参考