3 replies to this topic

[DOTOANNANG]

Với 3 số dương $a,\,b,\,c$ thì:

 

$$24\,\frac{a}{b+ c}+ 15\geqq 243\,\frac{a}{5\,a+ 2\,b+ 2\,c}$$

[DOTOANNANG]

$$4\,\frac{a}{b+ c}+ 1\geqq 9\,\frac{a}{a+ b+ c}$$

[VuQuyDat]

$$4\,\frac{a}{b+ c}+ 1\geqq 9\,\frac{a}{a+ b+ c}$$

$\Leftrightarrow (2a-b-c)^2\geq 0$

[VuQuyDat]

Với 3 số dương $a,\,b,\,c$ thì:

 

$$24\,\frac{a}{b+ c}+ 15\geqq 243\,\frac{a}{5\,a+ 2\,b+ 2\,c}$$

$\Leftrightarrow 120a^2-120a(c+b)+30(b+c)^2\geq 0\Leftrightarrow 30(2a-b-c)^2\geq 0$

Edited by VuQuyDat, 29-06-2018 - 23:11.