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Use Lagrange multipliers to find the maximum and minimum values of?

Use Lagrange multipliers to find the maximum and minimum values of f(x, y, z) = 3x + 3y + 5z on the sphere x^2 + y^2 + z^2 = 1.

1 Answer

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  • 7 years ago

    <3,3,5> = λ<2x,2y,2z>

    x²+y²+z²=1

    3/2 = λx

    3/2 = λy

    5/2 = λz

    (9/4) + (9/4) + (25/4) = 43/4 = λ² ⇒ λ = ±√43 / 2

    Plug those into the above and you'll get your maximum and minimum.

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