a)$(a+b+a)(\dfrac{1}{a}+\dfrac{1}{b}+\dfrac{1}{c}) $ 9
b)$\dfrac{a}{b+c}+\dfrac{b}{a+c}+\dfrac{c}{a+b}$ $\dfrac{3}{2}$
2) CMR a,b,c:
$\dfrac{a}{bc}+\dfrac{b}{ca}+\dfrac{c}{ab}$ 2.($\dfrac{1}{a}+\dfrac{1}{b}+\dfrac{1}{c}$)
3)Cho 0 x 3, 0 y 1. Tìm giá trị lớn nhất của:
$C=(3-x)(1-y)(4x+7y)$
Edited by loveboom, 20-09-2011 - 08:43.