Question

Using the given zero, find all other zeros of f(x).

-2i is a zero of f(x) = x4 - 21x2 - 100
@ganeshie8

Answer 1

let x^2=a

Answer 2

is is
-2i is a zero of f(x) = x^4 - 21x^2 - 100

Answer 3

\(\Large\color{blue}{ \bf hint.~~~~a^2-21a-100=(a -25)(a+4)}\)

Answer 4

2i, 5, -5

Answer 5

@SolomonZelman right?

Answer 6

@ganeshie8 help please!!

Answer 7

Correct !

Answer 8

\(\large\color{black}{ \bf x^2=25,~-4}\) THUS,

\(\large\color{black}{ \bf x=±5,±2i}\)

just -2i left out, but for other than that, you did a very good job, I actually like that :)