[pont494]

125.$x^4+1=18x^2$
$x^4+x^2+1=19x^2 ------------(1)$
$x^4-2x^2+1=16x^2$
$\sqrt{x^4-2x^2+1} =\sqrt{16x^2} $
$x^2-1=\pm 4x----------(2)$
$\frac{x^6-1}{x^3} = \frac{(x^2-1)(x^4+x^2+1)}{x^3} $
$= \frac{(\pm 4x)(19x^2)} {x^3} = \pm 76$