Question 272153
3x^4+15^2-72=0
{{{x^4 + 5x^2 - 24 = 0}}}
{{{(x^2 + 8)*(x^2 - 3) = 0}}}
x^2 = - 8
x = ± 2*i*sqrt(2) (complex numbers)
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x^2 = 3
x = ± sqrt(3)  (real numbers)