`\sqrt`

¶Synopsis, one of:

\sqrt{arg} \sqrt[root-number]{arg}

The square root, or optionally other roots, of `arg`. The optional
argument `root-number` gives the root, i.e., enter the cube root of
`x+y`

as `\sqrt[3]{x+y}`

.
The size of the radical grows with that of `arg` (as the height of
the radical grows, the angle on the leftmost part gets steeper, until
for a tall enough `arg`

, it is vertical).

LaTeX has a separate `\surd`

symbol for making a square root
without `arg` (see Math symbols).