Factor 121-y^2

$121 - y^{2}$

Step 1

Rewrite $121$ as $11^{2}$ .

$11^{2} - y^{2}$

Step 2

Since both terms are perfect squares, factor using the difference of squares formula, $a^{2} - b^{2} = (a + b) (a - b)$ where $a = 11$ and $b = y$ .

$(11 + y) (11 - y)$