If 3 x-1 3 x =5, find : 81 x^4+1 81 x^4 - Vidyadip

Question

If $3 x-\frac{1}{3 x}=5$, find : $81 x^4+\frac{1}{81 x^4}$

✓

Answer

$81 x^4+\frac{1}{81 x^4}$
$=\left(9 x^2+\frac{1}{9 x^2}\right)^2-2$
$=(27)^2-2$
$=729-2$
$=727$

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