Question

решите уравнение.
$9x {}^{4} - 9x {}^{2} + 2 = 0$
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Answer 1

$9x^4-9x^2+2=0\\D_x^2=81-8\cdot 9=81-72=9\\x^2=\cfrac{9\pm \sqrt{9}}{18}=\left \{ \cfrac{1}{3},\cfrac{2}{3} \right \}\Rightarrow x=\left \{ \pm \cfrac{1}{\sqrt{3}},\pm \sqrt{\cfrac{2}{3}} \right \}$