\[\boxed{\text{149\ (149).}\text{\ }\text{Еуроки\ -\ ДЗ\ без\ мороки}}\]
\[\textbf{а)}\ x^{4} = 6;\ \ \ \]
\[x \approx \pm 1,6.\]
\[\textbf{б)}\ x^{4} = 8,5;\ \ \ \ \]
\[x \approx \pm 1,7.\]