Given z = 1 − 2I, then 1z=______ .

Given z = 1 − 2I, then 1z=______ .

1z = 11 − 2I = 1 + 2I (1 − 2I) (1 + 2I) = 1 + 2i5 = 15 + 25i, so the answer is: 15 + 25i