1. Find the right circular cylinder of maximun volume that can be inscribed in a
sphere of radius 10 centimeters.
请问这题如何算
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2. Let f(x,y,z)=x+2xy-3z^2.Find the direction vector u along which the
directional derivative Duf at the point(1,0,4)reaches its maximum
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u =
第二题我算出来▽f(1,0,4)=(3,0,-24)
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那 u 的答案是 1.(3,0,-24)
2.1/[(9+(-24))^1/2](3i,-24k)
3.(3/[(9+(-24))^1/2)],0,-24/[(9+(-24))^1/2])
请问是用那个表示
以上请版友指导
※ 编辑: flygey 来自: 140.137.49.2 (07/03 13:59)
1F：推 ht15trep:2. 他要的只有方向, 所以(3,0,-24)即可 124.8.14.136 07/03 15:29
2F：→ ht15trep:1. 另为平面圆,极座标表高.半径,求极值 124.8.14.136 07/03 15:31
3F：→ ht15trep:1. 我算是2000π*[(√(2/3))^2]*√(1/3) 124.8.14.136 07/03 15:38