For the function $f(x)=\frac{x^2}{7x},$ find $f^{\text{'}\text{'}}(x).$ Then find $f^{\text{'}\text{'}}(0)$ and $f^{\text{'}\text{'}}(4).$

$f^{\text{'}\text{'}}(x)=$

$$

Select the correct choice below and fill in any answer boxes in your choice.

A$.f^{\text{'}}(0)=($Simplify your answer. Type an exact answer.$)$

B$.P^{\text{'}\text{'}}(0)$ is undefined.

Select the correct choice below and fill in any answer boxes in your choice.

A$.P^{\text{'}\text{'}}(4)=($Simplify your answer. Type an exact answer.$)$

$$ B$.f^{\text{'}\text{'}}(4)$ is undefined.