Show that (a) exp (2 3i) = -e2; (b) exp (2 + i/4) = e/2 (1 + i); (c) exp(z + i) = -

Show that
(a) exp (2 ± 3πi) = -e2;
(b) exp (2 + πi/4) = √e/2 (1 + i);
(c) exp(z + πi) = - exp z.