Answer:
1) 8 + 2i
2) -13
3) 15 + 3i
4) 1
5) 24 - 10i
Explanation:
Working with imaginary numbers is similar to working with a variable when it comes to addition and subtraction, so for problems 1 and 3, it is a matter of combining like terms.
1) The like terms are 7i and -5i; 5 and 3. We can combine them.
8 + 2i
2) We can start to compute the problem by noticing it is a special product of difference of squares. The expression can also be written as:
(3i)^2 - (2)^2
9i^2 - 4
i is defined as the square root of negative 1, so i^2 is -1. We can substitute that in:
9(-1) - 4
-9 - 4
-13
3) We can combine the like terms, 12i and -9i; 5 and 10:
15 + 3i
4)The powers of i repeat every four numbers. For example:
i^1 = i
i^2 = -1
i^3 = -i
i^4 = 1
i raised to a power divisible by four is always 1, so i^24 is 1.
5) We can start by normally distributing in this problem:
12 - 18i + 8i - 12i^2
As said before, i^2 is -1:
12 - 10i + 12
24 - 10i