Exercise Questions

I see that the minus sign in the equation $\delta_{i}^{\left(\mu, n_{\max }\right)}=E^{\prime}\left(\hat{y}_{i}^{\mu}\right) \cdot g^{\prime}\left(a_{i}^{\left(\mu, n_{\max }\right)}\right)$ was a typo and was removed, however all the solutions for parts b, c, and d still show the solutions as if there was a minus sign in the equation. Shouldn't they be changed as well?