To express \( 2^{-1} \) as a root, we start with the understanding that \( 2^{-1} \) is the same as \( \frac{1}{2} \).
Now, we can express \( \frac{1}{2} \) as a root:
\[ \frac{1}{2} = \frac{1}{\sqrt{4}} = \sqrt{\frac{1}{4}} = \sqrt{2^{-2}} = 2^{-1} = 2^{\frac{1}{2}} \]
Therefore, \( 2^{-1} = \frac{1}{2} \) can be written as
\[ \frac{1}{2} = \sqrt{2}^{-1} = 2^{-\frac{1}{2}} \]
So, \( 2^{-1} \) can be expressed as a root in the following way:
\[ 2^{-1} = \frac{1}{\sqrt{2}} \]
Hence:
\[ 2^{-1} = \sqrt{2}^{-1} \]
or, alternatively,
\[ 2^{-1} = 2^{1/2} \]
This represents \( 1/2 \) as a root.