Find the maximum and minimum values of the function f(x,y)=4𝑥^2 +9𝑦^2?

Update:

Find the maximum and minimum values of the function f(x,y)=4x^2 +9y^2

subject to xy = 4. Using Lagrange multipliers.

2 Answers

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  • rotchm
    Lv 7
    1 month ago

    Think when you were back in highschool (yes, this is a highschool question and does not involve any calculus). 

    Given two numbers x & y, what is the smallest possible value for

    4x² + 9y² ?

    Same question, but with greatest value...

  • It should be pretty easy to see that when you're at (0 , 0), you're at an absolute minimum.  (0 , 0 , 13).  Any non-zero value for x or y will result in something greater.  After that, there is no maximum.

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