Verified answer

[tex]\displaystyle\bf\\\sqrt[6]{b\sqrt[5]{b} } =\sqrt[6]{b\cdot b^{\frac{1}{5} } } =\sqrt[6]{b^{1+\frac{1}{5} } } =\\\\\\=\sqrt[6]{b^{1,2} } =b^{\frac{1,2}{6} } =b^{\frac{1}{5} } =\sqrt[5]{b}[/tex]