Answer
$3,9$
Work Step by Step
Given: $x^2-12x+27=0$
or, $x^2-12x=-27$
Add $(6)^2$ on both sides to make a perfect square.
Thus,
$x^2-12x+(6)^2=-27+(6)^2$
$x^2-2(x)(6)+36=9$
or, $(x-6)^2=9$
Apply Square root property.
$x=6\pm 3$
Hence,we have $x=3,9$
