作者monene5566 (机掰凯文)
看板trans_math
标题[微分] 89清大经济
时间Tue Jul 8 00:10:04 2008
2 2
Let f:| R --> | R be differentiable . Given u=(3/5,4/5), v=(4/5,-3/5)
2 ' 2 ' 2
prove that | gradient f | = |f_u| + |f_v|
' '
where f_u and f_v are the directional derivative of f in the direction
of u and v
这题不知道该怎样证 连第一步要怎样进行都无头绪
请版友解题了 谢谢:)
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