SOLUTION: i do not understand how x^4-9x^2 equals 20

Question 854182: i do not understand how x^4-9x^2 equals 20
Found 2 solutions by richwmiller, josgarithmetic:
Answer by richwmiller(17219) (Show Source): You can put this solution on YOUR website!
Who said it does?
Answer by josgarithmetic(39617) (Show Source): You can put this solution on YOUR website!

The equation is in quadratic form.
which seems not factorable.

Let v=x^2 and first solve for v.

Discriminant is and .

-
Remember how v was assigned and substituted.
, which is itself four different expressions, four different values.

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