Answer
Error $=(y-3)(y+3)$.
Correct solution $=(y-3)^2$.
Work Step by Step
The given polynomial is
$= y^2-6y+9$
Write the the polynomial as $a^2-2ab+b^2$.
$=y^2-2(y)(3)+3^2$.
Use perfect square trinomial pattern
$a^2-2ab+b^2=(a-b)^2$.
We have $a=y$ and $b=3$.
$=(y-3)^2$.
Hence, the error is $(y-3)(y+3)$ and the correct solution is $(y-3)^2$.
