Answer:
(3 - 2i)(5 + 3i)
Step-by-step explanation:
if we multiply both parenthesis we can see that 21 - i = (3 - 2i)(5 + 3i)
First multiply 3 with (5 - 3i)
3 × (5 5 3i) = 15 + 9i
then we multiply -2i with (5 - 3i)
-2i × (5 + 3i) = -10i - 6i^2 since -i^2 is equal to -1 we can write the expression like this -10i + 6
now we find the sum of expressions
15 + 9i - 10i + 6 = 21 - i
