Answer
$ (y+10)(y-10)$.
Work Step by Step
The given polynomial is
$= y^2-100$
Write the the polynomial as $a^2-b^2$.
$= y^2-100^2$
Use difference of two square pattern
$a^2-b^2=(a+b)(a-b)$.
We have $a=y$ and $b=10$.
$= (y+10)(y-10)$
Hence, the factor of the polynomial is $ (y+10)(y-10)$.
