Bai 1: cho \(n\inℕ^∗\). CMR : \(\frac{1}{2}.\frac{3}{4}.\frac{5}{6}.....\frac{2n-1}{2n}< =\frac{1}{\sqrt{3n+1}}\). <= nghia la be hon hoac bang nha cac ban
Bai 2 : Cho a>0;b>0. CMR : \(\frac{2\sqrt{ab}}{\sqrt{a}+\sqrt{b}}< =\sqrt{\sqrt{ab}}\)
Bai 3: Cho x, y, z > 0 và x + y + z = 1. Chứng minh rằng:\(\sqrt{x+yz}+\sqrt{y+zx}+\sqrt{z+xy}>=1+\sqrt{xy}+\sqrt{yz}+\sqrt{zx}\)