+129899 25x^4 - 20x^2 + 3 = 0 factor
(5x^2 - 3) (5x^2 - 1) = 0
Set each factor to 0 and solve
5x^2 - 3 = 0
add 3 to both sides
5x^2 = 3 divide both sides by 5
x^2 = 3/5 take both square roots
x = ± √(3/5)
Similarly.....setting the second factor to 0 and solving for x produces
x = ± √(1/5)
And those are the 4 solutions
