Let $x$ be a non-null quantity. Let $\hat{x}$ be its approximation. I am trying to find the relation between: $\frac{\left | x-\hat{x} \right |}{\left | x \right |}$ and $ \frac{\left | x-\hat{x} \right |}{\left | \hat{x} \right |}$?
According to what I understood, I did the following:
$\frac{\left | x-\hat{x} \right |}{\left | x \right |}=\frac{\left | x-\hat{x} \right |}{\left | \hat{x} \right |}\frac{\left | \hat{x} \right |}{\left | x \right |}$
but, I am not sure if this is how the problem is supposed to be solved. Any ideas? Thanks