\[x^{2} + 10x + 28 \geq 0\]
\[x^{2} + 10x + 25 + 3 \geq 0\]
\[(x + 5)^{2} + 3 \geq 0 \rightarrow \ верно\ \]
\[при\ любом\ x \in R.\ \]
\[Ответ:( - \infty; + \infty).\]