Question

So sánh

\(\sqrt{7}\)-\(\sqrt{15}\) và \(\sqrt{5}\) - \(\sqrt{3}\)

Answer 1

\(\sqrt{7}-\sqrt{15}< \sqrt{4}-\sqrt{16}=2-4=-2\)

\(\sqrt{5}-\sqrt{3}>\sqrt{4}-\sqrt{1}=2-1=1\)

Dễ nhận thấy:

\(\sqrt{7}-\sqrt{15}< \sqrt{5}-\sqrt{3}\)

Answer 2

\(\sqrt 7<\sqrt{15} \Rightarrow \sqrt 7-\sqrt{15}<0\\\sqrt 5>\sqrt 3\Rightarrow \sqrt 5-\sqrt 3>0\\\Rightarrow \sqrt 7-\sqrt{15}<\sqrt 5-\sqrt 3\)