((1+3i)/(1-2i))^2 i

(1+3i)(1+2i)

------------
(1-2i)(1+2i) all to the 2 i later

(1 + 5 i - 6)
-------------
(1 + 4 )

(5 i - 5)
---------
5

is

(i-1) so do (i-1) to the power