In equation 1d, we are using z_4^(i) to define z_4^(i) . In the context of 1a, would we set z_4^(i) in the left side 0?
Everything has to be moved to one side so that you have fbar(zbar^{(i)}) = 0bar
This is a nonlinear equation. You can’t solve for z_j^{(i)} explicitly.
You let Newton’s method do it iteratively.