\[\boxed{\text{875.}\text{\ }\text{еуроки}\text{-}\text{ответы}\text{\ }\text{на}\text{\ }\text{пятёрку}}\]
\[\textbf{а)}\ \sqrt{11} + 13 > \ \sqrt{15}\]
\[\sqrt{9} < \sqrt{11} < \sqrt{16}\]
\[3 + 13 < \sqrt{11} + 13 < 4 + 13\]
\[16 < \sqrt{11} + 13 < 17.\]
\[\sqrt{15} < \sqrt{16}\]
\[\sqrt{15} < 4.\]
\[\textbf{б)}\ \sqrt{84} < 7 + \sqrt{6}\]
\[\textbf{в)}\ \sqrt{8} - \sqrt{2} < 2\]
\[2,83 - 1,41 < 2.\]
\[\textbf{г)}\ \sqrt{47} - \sqrt{7} < 5\ \]
\[6,86 - 2,65 < 5.\]