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??
you need, of course, to factor this.
Start by doing this:
(x^2 - )(x^2 - ) =0
Can you fill in the blanks?
is it (x^2 - 6) (x^2 - 3) ??
yes!! so you have it factored. Then to get the "roots," set each one equal to 0.
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??
yes....
you have x^2 - 6 = 0,
so, x = + and - sqrt6
AND
x^2 - 3 = 0,
so, x also = + and - sqrt3