(a) Consider the function f: R² → R where f(x, y) = cos(x²y). (i) Find all the first and second order partial derivatives. (You may assume that fry = fyr.) (ii) Calculate the differential df of the function f(x, y) at the points (a,0), a € R and (0, b), b € R. (iii) Compute the directional derivative of f at (1, π/2) in the direction of v = i + j. (b) Consider the function g(x, y) = x² + 2xy + 2xy². (i) Show that (0, 0) is a critical point and find any other critical point(s) of g. (ii) Classify the critical point (0,0) of g(x, y) as a local maximum a local minimum or a

Linear Algebra: A Modern Introduction
4th Edition
ISBN:9781285463247
Author:David Poole
Publisher:David Poole
Chapter4: Eigenvalues And Eigenvectors
Section4.6: Applications And The Perron-frobenius Theorem
Problem 69EQ: Let x=x(t) be a twice-differentiable function and consider the second order differential equation...
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Part A Please solve in 10 minutes and get the thumbs up
(a) Consider the function f: R2 → R where
f(x, y) = cos(x²y).-
(i) Find all the first and second order partial derivatives. (You may assume that fay = fyx.)
(ii) Calculate the differential df of the function f(x, y) at the points (a,0), a € R and
(0, b), b = R.
(iii) Compute the directional derivative of f at (1, π/2) in the direction of v=i+j.
(b) Consider the function g(x, y) = x² + 2xy + 2xy².
(i) Show that (0, 0) is a critical point and find any other critical point(s) of g.
(ii) Classify the critical point (0, 0) of g(x, y) as a local maximum, a local minimum or a
saddle.
(iii) Is g(0,0) a global maximum of g(x, y), a global minimum of g(x, y) or neither? Justify
your answer.
Transcribed Image Text:(a) Consider the function f: R2 → R where f(x, y) = cos(x²y).- (i) Find all the first and second order partial derivatives. (You may assume that fay = fyx.) (ii) Calculate the differential df of the function f(x, y) at the points (a,0), a € R and (0, b), b = R. (iii) Compute the directional derivative of f at (1, π/2) in the direction of v=i+j. (b) Consider the function g(x, y) = x² + 2xy + 2xy². (i) Show that (0, 0) is a critical point and find any other critical point(s) of g. (ii) Classify the critical point (0, 0) of g(x, y) as a local maximum, a local minimum or a saddle. (iii) Is g(0,0) a global maximum of g(x, y), a global minimum of g(x, y) or neither? Justify your answer.
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