1)Find the local maximum and minimum values and

paris.richelle

paris.richelle

Answered question

2022-06-10

1)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) = y^2 − 10y cos x,    −1 ≤ x ≤ 7

2)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) = 7(x^2 + y^2)e^(y2 − x2)

Answer & Explanation

madeleinejames20

madeleinejames20

Skilled2023-05-20Added 165 answers

To find the local maximum and minimum values and saddle points of the function f(x,y)=y210ycos(x), we need to compute its first and second partial derivatives and analyze the critical points.
Let's begin by finding the first partial derivatives:
fx=10ysin(x)
fy=2y10cos(x)
To find the critical points, we set both partial derivatives equal to zero and solve the resulting system of equations:
10ysin(x)=0
2y10cos(x)=0
From the first equation, we have two possibilities:
1. 10y=0y=0
2. sin(x)=0x=kπ, where k is an integer
Substituting these possibilities into the second equation:
For y=0, we get 10cos(x)=0cos(x)=0x=π2+kπ, where k is an integer.
For sin(x)=0, we get 2y10=0y=102=5.
Therefore, the critical points are (π2+kπ,0) and (kπ,5), where k is an integer.
To determine the nature of these critical points, we need to compute the second partial derivatives:
2fx2=10ycos(x)
2fy2=2
2fxy=0
Now, we can evaluate the second partial derivatives at the critical points.
For the critical point (π2+kπ,0):
2fx2=0
2fy2=2
2fxy=0
For the critical point (kπ,5):
2fx2=10(5)cos(kπ)=(1)k·50
2fy2=2
2fxy=0
To classify the critical points, we can use the second partial derivative test:
1. For a critical point (π2+kπ,0), the second partial derivative test is inconclusive.
2. For a critical point (kπ,5):
- When k is even, the second partial derivative 2fx2=50>0, so we have a local minimum.
- When k is odd, the second partial derivative 2fx2=50<0, so we have a local maximum.
Therefore, the local maximum and minimum values of the function f(x,y) are obtained at the critical points (kπ,5), where k is an odd integer.
As for the saddle points, since the second partial derivative test is inconclusive for the critical points (π2+kπ,0), we cannot determine the presence of saddle points based on this analysis.
To graph the function f(x,y)=y210ycos(x), it is recommended to use three-dimensional graphing software to visualize the function's behavior accurately.

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