前两个小问是求函数的一阶偏导数，这三道题怎么做

Question

如题所述

Answer 1

A)
Z = lnsin(x-2y)
Z'x = cos(x-2y)/sin(x-2y) = cot(x-2y)..............(1)
Z'y = -cos(x-2y)/sin(x-2y) = -cot(x-2y)..........(2)
B)
U = x^(y/x)
lnU = ylnx/x
U'y/U = lnx/x
U'y ＝ （lnx/x）x^(y/x).............................(1)
U'x/U = y(1-lnx)/x^2
U'x = y(1-lnx)x^[(y/x)-2]..........................(2)
C)...................................