That looks good to me?

For a, we assume everything but z is constant, thus 4i goes to zero and (3-2i)z differentiates to (3-2i)

differentiate (3-2i)z+4i - Wolfram|Alpha

For b, it should be:

3z^2 -2(2+i)z + (1+3i), which is what you have. Yep all looks good to me?

differentiate z^3-(2+i)z^2+(1+3i)z-1 - Wolfram|Alpha