Question

x^4-28x^2=0 solve algebraically

Answer 1

$x^4 - 28x^2 = 0$

$x^2(x^2 - 28) = 0$

$x^2 = 0 \ \ or \ \ (x^2 - 28) = 0$

$x = 0 \ \ or \ \ x^2 = 28$

$x = 0 \ \ or \ \ x = \pm \sqrt{28}$

$x = 0 \ \ or \ \ x = \pm2 \sqrt{7}$

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Answer : x = 0 or 2√7 or -2√7
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