Question

X^4-3x^2-4=0
Using the quadratic formula

Answer 1

(-b ± (b^2 - 4 a c)^1/2) / 2 a is the quadratic formula (for x^2)

(3 ± (9 + 16)^1/2) / 2 = (3 + 5) / 2 = 4

x^2 = ± 4 and x = ± 2

Check:

Let Y = X^2 and the equation becomes

Y^2 - 3 Y - 4 = 0

(Y + 1) ( Y - 4) = 0

Y = 4 is one answer or x^2 = 4 and x = 2

Also 2^4 - 3 2^2 - 4 = 16 - 3 * 4 - 4 = 0