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rezolvati ecuatia: z^3+8=0 (nr complexe)

Răspuns :

z^3 + 8 = 0 
z^3 = - 8 
z^3 = (-2)^3 
z = -2 
z³+8=0
z³+2³=0
(z+2)(z²-2z+4)=0

z+2=0       z=-2

z²-2z+4=0

Δ=(-2)²-4×1×4=4-16=-12     i²=-1    Δ=12i²
z₁=(2-√12i²)/2=(2-2i√3)/2=1-i√3
z₂=(2+√12i²)/2=(2+2i√3)/2=1+i√3