You know Sasini, I do not think I answered the intended question.
I might try it again. (It is written in Russian)
I use Bing or Google translators to make sense of these.
I might try looking at this question a more straight forward way.
$$\\NOTE: \;\;x+4>0\;\;so\;\;x>-4\\\\
log_{\sqrt2}(x+4)\le2\\\\
\frac{log(x+4)}{log{\sqrt2}}\le2\\\\
log(x+4)\le 2log\sqrt2\\\\
log(x+4)\le 2log(2^{1/2})\\\\
log(x+4)\le log(2)\\\\
x+4\le2\\\\
x \le -2\\\\
therefore\qquad -4
slight errors corrected - thanks Chris :))
Here is the Wolfram|Alpha solution and graph
http://www.wolframalpha.com/input/?i=log%28x%2B4%29%2Flog%28sqrt2%29%3C2