Chapter 12 Page 711 Questions 22-24

For all questions, find fx, fy, fxx, fyy, fxy, and fyx:

Question 22:

\(f(x, y) = 5x - 17y\)

\(f_x = 5\)

\(f_y = -17\)

\(f_xx = 0\)

\(f_yy = 0\)

\(f_xy = 0\)

\(f_yx = 0\)

Question 23

\(f(x, y) = 3x^2 + 1\)

\(f_x = 6x\)

\(f_y = 0\)

\(f_xx = 6\)

\(f_yy = 0\)

\(f_xy = 0\)

\(f_yx = 0\)

Question 24

\(f(x, y) = ln(x^2 + y)\)

\(f_x = \frac{2x}{x^2 + y}\)

\(f_y = \frac{1}{x^2 + y}\)

\(f_{xx} = \frac{-2x^2 + 2y}{(x^2 + y)^2}\)

\(f_{yy} = - \frac{1}{(x^2 + y)^2}\)

\(f_{xy} = - \frac{2x}{(x^2 + y)^2}\)

\(f_{yx} = - \frac{2x}{(x^2 + y)^2}\)

Issues:

I found questions 22 and 23 were very simple cases. I hope I did not miss anything in these two questions. In question 24, the derivatives were challenging. I am unsure if \(f_{xy}\) and \(f_{yx}\) should be equal like I found. If you find an issue with my solutions, please let me know. Thank you!

What were the most valuable elements you took away from this course?