Find all cubic roots of z = −1 + i

Hi Gibsonj338   

Find all cubic roots of

 $z=-1+i \mbox{ distance of z to the origin }=\sqrt{1^2+1^2}=\sqrt2\\ \mbox{cubic toots so there are 3 of them so they are } \frac{2\pi}{3} radians\; apart.\\ z=\sqrt2(cis\frac{3\pi}{4})\\ \sqrt[3]{z}=\sqrt[6]{2}(cis(\frac{3\pi}{4}\div3)),\quad\sqrt[6]{2}(cis((\frac{3\pi}{4}+2\pi)\div3)),\quad \sqrt[6]{2}(cis((\frac{3\pi}{4}+4\pi)\div3))\\ \sqrt[3]{z}=\sqrt[6]{2}(cis(\frac{3\pi}{4}\div3)),\quad\sqrt[6]{2}(cis(\frac{11\pi}{4}\div3)),\quad \sqrt[6]{2}(cis(\frac{19\pi}{4}\div3))\\ \sqrt[3]{z}=\sqrt[6]{2}(cis(\frac{3\pi}{12})),\quad\sqrt[6]{2}(cis(\frac{11\pi}{12})),\quad \sqrt[6]{2}(cis(\frac{19\pi}{12}))\\ \sqrt[3]{z}=\sqrt[6]{2}(cis(\frac{\pi}{4})),\quad\sqrt[6]{2}(cis(\frac{11\pi}{12})),\quad \sqrt[6]{2}(cis(\frac{19\pi}{12}))\\ or\ $

$\sqrt[3]{z}=\frac{1+i}{\sqrt[3]{2}},\quad\sqrt[6]{2}(cos(\frac{11\pi}{12})+i\;sin(\frac{11\pi}{12})),\quad\sqrt[6]{2}(cos(\frac{19\pi}{12})+i\;sin(\frac{19\pi}{12}))\\ \sqrt[3]{z}=\frac{1+i}{\sqrt[3]{2}},\quad\sqrt[6]{2}(-cos(\frac{\pi}{12})+i\;sin(\frac{\pi}{12})),\quad\sqrt[6]{2}(cos(\frac{5\pi}{12})-i\;sin(\frac{5\pi}{12}))$

$z =(−1 + i )^(1/3)$

$r=\sqrt((-1)^2+1^2)$

$r=\sqrt(1+1^2)$

$r=\sqrt(1+1)$

$r=\sqrt(2)$

$tan(\Theta)=1/-1$

$tan(\Theta)=-1$

$\Theta=tan^-1(-1)$

$\Theta=-\pi/4$

$\sqrt(2)e^(-\pi/4i)^(1/3)$

$\sqrt(2)^(1/3)e^(-\pi/12i)$

$\sqrt(2)^(1/3)*(cos(-\pi/12)+isin(-\pi/12))$

$\sqrt(2)^(1/3)*(0.965925826289 +isin(-\pi/12))$

$\sqrt(2)^(1/3)*(0.965925826289 +i*-0.258819045103)$

$\ 1.414213562373095)^(1/3)*(0.965925826289 +i*-0.258819045103)$

$\ 1.122462048309373*(0.965925826289 +i*-0.258819045103)$

$\ 1.084215081491274550528506797 +i*-0.290514555507789375384650419$

$\ 1.084215081491274550528506797 + -0.290514555507789375384650419i$

Answer 1:$\ 1.084215081491274550528506797 -0.290514555507789375384650419i$

$\sqrt(2)e^(7\pi/4i)^(1/3)$

$\sqrt(2)^(1/3)e^(7\pi/12i)$

$\sqrt(2)^(1/3)*(cos(7\pi/12)+isin(7\pi/12))$

$\sqrt(2)^(1/3)*(-0.258819045103 +isin(7\pi/12))$

$\sqrt(2)^(1/3)*(-0.258819045103 +i* 0.965925826289)$

$\ 1.414213562373095)^(1/3)*(-0.258819045103 +i* 0.965925826289)$

$\ 1.122462048309373*(-0.258819045103 +i* 0.965925826289)$

$\ -0.290514555507789375384650419 +i* 1.084215081491274550528506797$

Answer 2:$\ -0.290514555507789375384650419 +1.084215081491274550528506797i$

$\sqrt(2)e^(15\pi/4i)^(1/3)$

$\sqrt(2)^(1/3)e^(15\pi/12i)$

$\sqrt(2)^(1/3)*(cos(15\pi/12)+isin(15\pi/12))$

$\sqrt(2)^(1/3)*(-0.707106781187 +isin(15\pi/12))$

$\sqrt(2)^(1/3)*(-0.707106781187 +i* -0.707106781187)$

$\ 1.414213562373095)^(1/3)*(-0.707106781187 +i* -0.707106781187)$

$\ 1.122462048309373*(-0.793700525984607637192165751 +i* -0.793700525984607637192165751)$

$\ -0.793700525984607637192165751 +i*-0.793700525984607637192165751$

$\ -0.793700525984607637192165751 +-0.793700525984607637192165751i$

Answer 3:$\ -0.793700525984607637192165751 -0.793700525984607637192165751i$