Question

Why is the completely factored form X^4+8x^2-9

Answer 1

Greetings!

This is still factor-able:

`x^4+8x^2-9`

`x^4+9x^2-x^2-9`
Factor by grouping.

`x^2(x^2+9)-1(x^2+9)`

`(x^2+9)(x^2-1)`
Factor by difference in squares.

`(x^2+9)(x-1)(x+1)`

Hope this helps.
-Benjamin