Question

use variable substitution and factoring to find all of the roots of each equation.

x^4-9x^2+18=0

how do you do this??

Answer 1

you need, of course, to factor this.
Start by doing this:

(x^2 - )(x^2 - ) =0

Can you fill in the blanks?

Answer 2

is it (x^2 - 6) (x^2 - 3) ??

Answer 3

yes!! so you have it factored. Then to get the "roots," set each one equal to 0.

Answer 4

so then its x^2-6 =0 and ^2-3=0 and the don't i put the root sign over the x^2 to get rid of the x^2? and then i end up with x + or - the suare root of 6 = 0 or is that wrong??

Answer 5

yes....
you have x^2 - 6 = 0,
so, x = + and - sqrt6

AND

x^2 - 3 = 0,
so, x also = + and - sqrt3

Answer 6

so is that it?? simple as that?

Answer 7

yup, simple as that!!

Answer 8

but then the directions say variable substitution

Answer 9

I'm sorry. I really don't know what they mean by "variable substitution!"

Answer 10

alright thanks anyway

Answer 11

x^2-x-?=(x+2)(x-?)