Question 119955
It can't be because of the (-) sign in front of the 81
The perfect square can only have two forms
{{{(x - a)^2 = 0}}}
or
{{{(x + a)^2 = 0}}}
The 1st gives me
{{{x^2 - 2a + a^2 = 0}}}
and the 2nd gives me
{{{x^2 + 2a + a^2 = 0}}}
Notice that the sign in front of the constant term, {{{a^2}}} is
(+) in both cases