Question

Simplify the given expression:

(_5 + 3i) ´ (1 _ 2i)
I've been having trouble with these... I use FOIL and then combine like terms but the answer I come up with is never an option. These are my four options the closest one to my answer is the second one.
_5 _ 6i
1 + 13i
2 + i
4 _ 5i

Answer 1

We will multiply the two using the distributive property:
-5(1 - 2i) + 3i(1 - 2i)
= -5 + 10i + 3i - 6i²
Now, i² = -1
= -5 + 10i + 3i -6(-1)
= 6 - 5 + 10i + 3i
= 1 + 13i
The second option is correct.