Something on the right of a radical

From Why start at x, y, z

A square root is often shown with a radical symbol: \( \sqrt{x} \). The top line is drawn as wide as it needs to be to cover the whole radicand:

\[ \sqrt{x^2 + 2x + 1} \]

But it can be easy to misinterpret an expression where there's something on the right of the radical:

\[ \sqrt{x^2 + 2x + 1}a \]

This is particularly problematic in handwriting.

The usual way of resolving this is to put the other thing on the left instead:

\[ a\sqrt{x^2+2x+1} \]

However, when the radical contains a single letter or number, it's more common to put the radical on the left:

\[ \sqrt{2} \sin x \]

See The order of factors matters even when they commute