Chứng minh :
1. $\frac{x^2}{y^2+z^2}+\frac{y+z}{4}\geq x$ ($x;y;z> 0$)
2. $\frac{a}{\sqrt{b}}+\sqrt{a}\geq \sqrt{b}-\frac{b}{\sqrt{a}} \left ( a;b\geq 0 \right )$
3. $x^4+y^4\leq \frac{x^6}{y^2}+\frac{y^6}{x^2}\left ( x;y\neq 0 \right )$
4. $\frac{2\sqrt{ab}}{\sqrt{a}+\sqrt{b}}\leq \sqrt[4]{ab}\left ( a;b> 0 \right )$
5. $y\left ( \frac{1}{x}+\frac{1}{z} \right )+\frac{1}{y}\left ( x+z \right )\leqslant \frac{\left ( x+z \right )^2}{xz}$ ($0< x\leq y\leq z$)
6. $\sqrt{2x^2-2x+5}+\sqrt{2x^2-4x+4}\geq \sqrt{13}$
7. $a^3+b^3+c^3\geq a^2\sqrt{bc}+b^2\sqrt{ac}+c^2\sqrt{ab}\left ( a;b;c>0 \right )$
8. $x(x-y)(x-z)+y(y-x)(y-z)+z(z-x)(z-y)\geq 0\left ( x;y;z\geq 0 \right )$
9. Cho $a;b;c$ là độ dài 3 cạnh tam giác . $\left ( \sqrt[3]{a}+\sqrt[3]{b}+\sqrt[3]{c} \right )\left ( \frac{1}{\sqrt[3]{a}}+\frac{1}{\sqrt[3]{b}}+\frac{1}{\sqrt[3]{c}} \right )-\frac{a+b+c}{abc}\leq 6$
10. $\frac{a^4}{(a+b)(a^2+b^2)}+\frac{b^4}{(b+c)(b^2+c^2)}+\frac{c^4}{(c+d)(c^2+d^2)}+\frac{d^4}{(d+a)(d^2+a^2)}\geq \frac{a+b+c+d}{4}\left ( a;b;c;d\geq 0 \right )$
Bài viết đã được chỉnh sửa nội dung bởi huy2403exo: 23-10-2014 - 11:09