Math-related pictures: 5

Pages 1, 2, 3, 4, 5, 6.

Find a mistake in the following reasoning (if there is any):

$\begin{displaymath} -1=\sqrt[3]{-1}=(-1)^{\frac{1}{3}}= (-1)^{\frac{2}{6}}=\left((-1)^2\right)^{\frac{1}{6}}= 1^{\frac{1}{6}}=1 \end{displaymath}$