High School

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

Select the product:

A. 39

B. 89

C. [tex]$39 - 80i$[/tex]

D. [tex][tex]$89 - 80i$[/tex][/tex]

Answer :

To simplify the expression

[tex]$$
(8-5i)^2,
$$[/tex]

we start by writing the square as a product:

[tex]$$
(8-5i)(8-5i).
$$[/tex]

Now, we expand the product using the distributive property (FOIL method):

1. Multiply the first terms:
[tex]$$
8 \times 8 = 64.
$$[/tex]
2. Multiply the outer terms:
[tex]$$
8 \times (-5i) = -40i.
$$[/tex]
3. Multiply the inner terms:
[tex]$$
(-5i) \times 8 = -40i.
$$[/tex]
4. Multiply the last terms:
[tex]$$
(-5i) \times (-5i) = 25i^2.
$$[/tex]

Next, add all these results together:

[tex]$$
64 - 40i - 40i + 25i^2 = 64 - 80i + 25i^2.
$$[/tex]

Recall that [tex]$i^2 = -1$[/tex]. Thus, we substitute:

[tex]$$
25i^2 = 25(-1) = -25.
$$[/tex]

Now, replace [tex]$25i^2$[/tex] with [tex]$-25$[/tex] in the expression:

[tex]$$
64 - 80i - 25.
$$[/tex]

Finally, combine the real numbers:

[tex]$$
64 - 25 = 39.
$$[/tex]

So, the simplified form is:

[tex]$$
39 - 80i.
$$[/tex]

Thus, the product is [tex]$\boxed{39-80i}$[/tex].