independence of valuations

Let $|\cdot|_1$ , ..., $|\cdot|_n$ be non-trivial (i.e., they all have also other values than 0 and 1) and pairwise non-equivalent valuations of a field $K$ , all with values real numbers. If $a_1$ , ..., $a_n$ are some elements of this field and $\varepsilon$ is an arbitrary positive number, then there exists in $K$ an element $y$ which satisfies the conditions