Question 196635
The constant a represents a positive real number. 
a^3x^3 + 64 = 0 
(ax+4)*(a^2x^2 - 4ax + 16) = 0
x = -4/a
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*[invoke solve_quadratic_equation 1,-4,16]
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Reducing gives:
2 ± isqrt(12)
Then taking the "a" into account:
x = (2 ± 2i*sqrt(3))/a