Răspunsuri

2014-07-10T12:41:22+03:00
Facem subtitutia x=y+ \frac{2}{y} . Ecuatia se scrie:
(y+ \frac{2}{y} )^3-6(y+ \frac{2}{y} )-6=0\\
y^6-6y^3+8=0\\
y^3=z\\
z^2-6z+8=0\\
z= 4 sau 2\\
y^3=4=>y=\sqrt[3]{4}=>x=\sqrt[3]{4}+ \frac{2}{\sqrt[3]{4}} =\sqrt[3]{4}+\frac{\sqrt[3]{8}}{\sqrt[3]{4}}\\
x=\sqrt[3]{4}+\sqrt[3]{2}