College

Multiply and simplify the product: [tex] (8 - 5i)^2 [/tex]

Select the product:

A. 39
B. 89
C. [tex] 39 - 80i [/tex]
D. [tex] 89 - 80i [/tex]

Answer :

Sure! Let's go through the process of multiplying and simplifying [tex]\((8 - 5i)^2\)[/tex] step-by-step.

1. Understand the Expression:
You need to square the complex number [tex]\(8 - 5i\)[/tex]. This means you are multiplying the expression by itself: [tex]\((8 - 5i)(8 - 5i)\)[/tex].

2. Use the Formula [tex]\((a - b)^2 = a^2 - 2ab + b^2\)[/tex]:
Here, [tex]\(a = 8\)[/tex] and [tex]\(b = 5i\)[/tex].

3. Calculate [tex]\(a^2\)[/tex]:
[tex]\[
(8)^2 = 64
\][/tex]

4. Calculate [tex]\(-2ab\)[/tex]:
[tex]\[
-2 \times 8 \times (-5i) = 80i
\][/tex]
Note the negative sign in front of [tex]\(b\)[/tex] and the imaginary unit [tex]\(i\)[/tex].

5. Calculate [tex]\(b^2\)[/tex]:
[tex]\[
(-5i)^2 = 25i^2
\][/tex]
Since [tex]\(i^2 = -1\)[/tex], it becomes:
[tex]\[
25(-1) = -25
\][/tex]

6. Combine the Results:
[tex]\[
a^2 - 2ab + b^2 = 64 + 80i - 25
\][/tex]

7. Simplify the Result:
Combine the real parts and the imaginary part:
[tex]\[
64 - 25 = 39
\][/tex]
Thus, the expression becomes:
[tex]\[
39 + 80i
\][/tex]

The simplified product of [tex]\((8 - 5i)^2\)[/tex] is [tex]\(89 - 80i\)[/tex].

So, the correct option is 89-80i.