factor completely. $u^{2}-4u + 4$

$factor completely. $u^{2}-4u + 4$$

The expression $u^{2}-4u + 4$ is in the form of $a^{2}-2ab + b^{2}$, where $a = u$ and $b=2$.

The perfect - square formula is $a^{2}-2ab + b^{2}=(a - b)^{2}$. Substituting $a = u$ and $b = 2$ into the formula, we get $(u - 2)^{2}$.

$(u - 2)^{2}$