# Is the following trinomial  x^2 + 18x + 81 a perfect square?

Since ${x}^{2} + 18 x + 81 = {\left(x + 9\right)}^{2}$
${x}^{2} + 18 x + 81$ is considered a perfect (polynomial) square
even though (if $x$ is not an integer) its value might not be a perfect square.