Find the local maximum and minimum values and

Answered question

2022-03-30

Find the local maximum and minimum values and saddle point(s) of the function. If you have three-dimensional graphing software, graph the function with a domain and viewpoint that reveal all the important aspects of the function. (Enter your answers as a comma-separated list. If an answer does not exist, enter DNE.)

f(x, y) = 3 − 2x + 4yx2 − 4y2

local maximum value(s)       
local minimum value(s)       
saddle point(s)    (x, y, f)  

Answer & Explanation

star233

star233

Skilled2023-04-26Added 403 answers

To find the local maximum and minimum values and saddle point(s) of the function
f(x,y)=32x+4yx24y2
we need to find the critical points and determine their nature using the second partial derivative test.
First, we take the partial derivatives of f with respect to x and y:
fx=2x2andfy=48y
Next, we set these partial derivatives equal to zero and solve for x and y:
2x2=0x=1
48y=0y=12
Therefore, the only critical point of f is (1,12).
To determine the nature of this critical point, we need to compute the second partial derivatives of f:
2fx2=22fxy=02fy2=8
At the critical point (1,12), we have:
D=2fx22fy2(2fxy)2=(2)(8)(0)2=16>0
and
2fx2=2<0
Therefore, the critical point (1,12) is a local maximum of f.

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