-3 [ 1 -2 0 - 4 4 ]
-3 15 -45 147
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1 -5 15 -49 151
x^4 - 41x^2 = -400
x^4 - 41x^2 + 400 = 0 factor as
(x^2 - 25) (x^2 - 16) = 0
(x + 5) (x - 5)(x + 4) (x - 4) = 0
Setting each factor and solving for x produces the real roots -5, 5, -4, 4