a) ta có \(\sqrt{27}>\sqrt{25}=5\)
\(\sqrt{6}>\sqrt{4}=2\)
Suy ra \(\sqrt{27}+\sqrt{6}+1>5+2+1=8\)
Ta có 64>48\(\Rightarrow\sqrt{64}>\sqrt{48}\Rightarrow8>\sqrt{48}\)
Vậy \(\sqrt{27}+\sqrt{6}+1>\sqrt{48}\)
b) Ta có \(\sqrt{15}.\sqrt{17}=\sqrt{255}\)
Ta lại có 324>255\(\Rightarrow\sqrt{324}>\sqrt{255}\Rightarrow18>\sqrt{255}\)
Vậy \(18>\sqrt{15}.\sqrt{17}\)