Question

So Sánh  \(4\) và \(4\sqrt{5}-\sqrt{26}\)(ko Dùng máy tính)

Answer 1

Ta có:\(4\sqrt{5}-\sqrt{26}=\sqrt{16}.\sqrt{5}-\sqrt{26}\)

\(=\sqrt{80}-\sqrt{26}\)

\(< \sqrt{81}-\sqrt{26}< \sqrt{81}-\sqrt{25}\)

\(=9-5=4\)

Vậy \(4>4\sqrt{5}-\sqrt{26}\)