Question

Which of the following is a polynomial with roots 2, –3i, and 3i ?

Answer 1

options:
x3 + 4x2 + 9x + 24

x3 – 4x2 + 9x – 24

x3 + 2x2 + 9x + 18

x3 – 2x2 + 9x – 18

Answer 2

help please?

Answer 3

(x-2)(x+3i)(x-3i)

Answer 4

expand the equation

Answer 5

(x-2)(x^2+9)

Answer 6

can you do the rest?

Answer 7

I've been having a lot of trouble with it, would you mind working it out for me?

Answer 8

Well sure

Answer 9

The first step is given by the equation

Answer 10

(x-2)(x+3i)(x-3i)

Answer 11

Those are the roots of the equation... The answers in the parenthesis will get you 0 if you put in the 2,3i and -3i for x.

Answer 12

then when multiplying it out to get the equation i did the part with 3i and -3i first

Answer 13

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

Answer 14

i^2 = -1

Answer 15

and the terms in the middle cancel out

Answer 16

so that gets you x^2 + 9

Answer 17

then you multiply that with (x-2)

Answer 18

(x-2)(x^2+9)= x^3 + 9x - 2x^2 -18

Answer 19

rearrange the terms and there is your answer

Answer 20

Any questions?

Answer 21

ohhh so it's the last one right? now it makes sense to me

Answer 22

No problem. =D