19.5. Prove the following identities for differentiation by finding the real and imaginary parts of the functionu(r, y) and v(x, y)-and differentiat- ing them: df dg df dz f'(z)g(z) – g'(z)f(z) g(2)]2...

hi...

in the picture.

Extracted text: 19.5. Prove the following identities for differentiation by finding the real and imaginary parts of the functionu(r, y) and v(x, y)-and differentiat- ing them: df dg df dz f'(z)g(z) – g'(z)f(z) g(2)]2 (a) 부(+9)=a dg (b) 는(f9)=D9+ f군 g+f. dz dz dz dz (c) where g(z) # 0. (6)