Question

помогите!!
$a - \frac{1}{a} = 3 \sqrt{2}$
если так, то
$a {}^{2} + \frac{1}{a {}^{2} } =$
?????​

Answer 1

$a-\frac{1}{a}=3\sqrt{2}\\\\(a-\frac{1}{a})^{2} =(3\sqrt{2})^{2}\\\\a^{2}-2*a*\frac{1}{a} +\frac{1}{a^{2}}=18\\\\a^{2}-2+\frac{1}{a^{2}}=18\\\\a^{2}+\frac{1}{a^{2}}=18+2\\\\\boxed{a^{2}+\frac{1}{a^{2}}=20}$

Answer 2

Ответ во вложении.

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