Question

which of the following is a polynominal with roots 2, -3i,and3i?

Answer 1

the one that looks like
\[(x-2)(x+3i)(x-3i)\] after you multiply out

Answer 2

not as hard as it looks since \((x+3i)(x-3i)=x^2+9\) so really you have to multiply \[(x-2)(x^2+9)\]

Answer 3

what i don't understand is the 3i.

Answer 4

it is another name for \(3\sqrt{-1}\)

Answer 5

oh. okay. i got it :) Thank you.

Answer 6

\(i=\sqrt{-1}\) by definition so if you solve
\[x^2+9=0\] you get \(x^2=-9\) or \(x=\pm3i\)

Answer 7

yw