Question

Please help 50 point !!

Answer 1

Answer:

The last one

Step-by-step explanation:

$x^3+1=0$

Subtract 1 from both sides

$x^3+1-1=0-1$

simplify

$x^3=-1$

$\mathrm{For\:}x^3=f\left(a\right)\mathrm{\:the\:solutions\:are\:}x=\sqrt[3]{f\left(a\right)},\:\sqrt[3]{f\left(a\right)}\frac{-1-\sqrt{3}i}{2},\:\sqrt[3]{f\left(a\right)}\frac{-1+\sqrt{3}i}{2}$

$x=\sqrt[3]{-1},\:x=\sqrt[3]{-1}\frac{-1+\sqrt{3}i}{2},\:x=\sqrt[3]{-1}\frac{-1-\sqrt{3}i}{2}$

simplify

$x=-1,\:x=\frac{1}{2}-i\frac{\sqrt{3}}{2},\:x=\frac{1}{2}+i\frac{\sqrt{3}}{2}$

(That's basically the last one but in a different way of writing it)