0}|-|\underbrace {\sqrt7+\sqrt4}_{>0}|=\\\\=\sqrt7-\sqrt4-(\sqrt7+\sqrt4)=\sqrt7-2-\sqrt7-2=-4" alt="\sqrt{11-2\sqrt{28}}-\sqrt{11+2\sqrt{28}}=\sqrt{11-2\sqrt4\cdot \sqrt7}-\sqrt{11+2\sqrt4\cdot \sqrt7}=\\\\=\sqrt{(\sqrt7-\sqrt4)^2}-\sqrt{(\sqrt7+\sqrt4)^2}=|\underbrace {\sqrt7-\sqrt4}_{>0}|-|\underbrace {\sqrt7+\sqrt4}_{>0}|=\\\\=\sqrt7-\sqrt4-(\sqrt7+\sqrt4)=\sqrt7-2-\sqrt7-2=-4" align="absmiddle" class="latex-formula">
Число (-4) - целое число.