no because it would be
if you knew that
ax^2+bx+c was a trinomial square, then the factored form would be
\(( \sqrt{a}x+ \sqrt{c})^{2}\) or \(( \sqrt{a}x- \sqrt{c})^{2}\)
so
if w^2-9w+81 is perfect square, factored form is either
\(( \sqrt{1}x+ \sqrt{81})^{2}\) or \(( \sqrt{1}x- \sqrt{81})^{2}\) aka \(( x+9)^{2}\) or \(( x-9)^{2}\)
expand them
(x+9)^2=x^2+18x+81, wron middle term
(x-9)^2=x^2-18x+81 wrong
so it is not
