Answer:
7 - i
Explanation:
Standard form of a complex number is a + bi. The a represents the real part and bi represents the imaginary part.
Keep in mind that i^2 = -1.
To simplify this complex number expression first distribute -5 inside the parentheses.
-5(1 + 2i) ⇒ -5 - 10i
Now distribute 3i inside the parentheses.
3i(3 - 4i) ⇒ 9i - (-12)
Put both of these expressions together and combine like terms as normal.
-5 - 10i + 9i + 12
-5 + 12 = 7
-10i + 9i = -i
We are left with 7 - i as our answer. This is already in standard form of a complex number, therefore, it is our final answer.