Question

Which shows x^2+9 factored over the set of complex numbers?
a. (x+3i)^2
b. (x+3i)(x-3i)
c. (x-1)(x+9i)
d. (-x+3i)(x-3i)

Answer 1

HINT: (a+b)(a-b)=a^2-b^2

Answer 2

Okay! Thanks, I'm going to try that

Answer 3

I think the answer is A. Is that correct?

Answer 4

No.

Answer 5

Okay, then I think its b

Answer 6

Why?

Answer 7

because (x+3i)(x-3i)= x^2+9

Answer 8

Did you expand it out?

Answer 9

No I didn't expand it.

Answer 10

You'll never know the answer.

Answer 11

Dude, are you gonna help me or not?

Answer 12

do you know how to expand it out?

Answer 13

I'm not going to tell you the answer, but I will help you if you are willing to put forth effort.

Answer 14

If you don't know how to expand it out here is an example

\[(x+3i)^2\]
(x+3i)(x+3i)
x^2 +3i +3i +9i^2 (i^2 is 1 so its just 9*1)
\[x^2 +6i +9 \]

Answer 15

my mistake i^2 is actually -1 so the answer would be
\[x^2 +6i -9\]

Answer 16

All in all your answer is B if you never figured it out