Determine if the Expression is a Perfect Square x^2-18x

$x^{2} - 18 x$

A trinomial can be a perfect square if it satisfies the following:

The first term is a perfect square.

The third term is a perfect square.

The middle term is either $2$ or $- 2$ times the product of the square root of the first term and the square root of the third term.

${(a - b)}^{2} = a^{2} - 2 a b + b^{2}$

The polynomial does not satisfy all qualifiers for being a perfect square.

The polynomial is not a perfect square