[微積] 95 清大計財A, 多變函數限制條件求極值
Find the minimum of f(x,y,z) = 3x + 2y + z + 5, subject to the
constraint g(x,y,z) = 9x^2 + 4y -z = 0.
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令 L(x,y,z,λ) = (3x+2y+z+5) + λ(9x^2+4y-z)
取 gra(L) = 0
得到 L_x = 3 + 18λx = 0
L_y = 2 + 4λ = 0
L_z = 1 - λ = 0
二式三式條件解出來的 λ 不相等,
是都要考慮然後分別代回嗎?
還是就是這題無解了?
可是即使帶回後,條件似乎也不太足夠得到 x y z 間的關係…
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