Answer:
A.
= 8i
B. 8i + 5i = 13i
C. 8i - 5i = 3i
D. 8i x 5i = -40
Explanation:
A. The square root of any negative number would lead to a complex number. Complex numbers are number which consist a complex part denoted by i.
-1 =

=
= i
Example: 1. What is the square root of -64?
square root of -64 =

=

=
x

= i x 8
= 8i
= 8i
2. find the square root of -25.
=

= 5i
B. To add two complex numbers, they are considered as algebraic expressions.
Example, the sum of 8i and 5i can be determined as;
8i + 5i = 13i
C. To add two complex numbers, they are considered as algebraic expressions.
Example, the subtraction of 8i and 5i can be determined as;
8i - 5i = 3i
D. To multiply two complex numbers, the complex part is considered.
Example, determine the product of 8i and 5i.
8i x 5i = 8 x 5 x i x i
= 40

= -40 (∵
= -1)
8i x 5i = -40