a,b,c>0.CMR a^2/(2a+b)(2a+c)+b^2/(2b+c)(2b+a)+c^2/(2c+a)(2c+b) >1/3
a,b,c>0: a+b+c=3. Chứng minh:
\(a^2b+b^2c+c^2a>=\frac{9a^2b^2c^2}{1+2a^2b^2c^2}\)
Bài 5: cho a,b,c lớn hơn 0
chứng minh rẳng:
\(2\left(\dfrac{a}{b+2c}+\dfrac{b}{c+2a}+\dfrac{c}{a+2b}\right)\ge1+\dfrac{b}{b+2a}+\dfrac{c}{c+2b}+\dfrac{a}{a+2c}\)
c/m : 2(a/(b+2c)+b/(c+2a)+c/(a+2b)) - (b/(b+2a)+c/(c+2b)+a/(a+2c)) >= 1
Cho a, b, c là độ dài 3 cạnh tam giác. CMR:\(a^2b+b^2c+c^2a+a^2c+c^2b+b^2a-a^3-b^3-c^3>0\)
Cho a,b,c là các số dương thỏa mãn a+b+c=3. CMR : a^2b + b^2c + c^2a >= 9a^2b^2c^2/(1+2a^2b^2c^2
Cho 0<a,b,c<1.CMR:
2a^3+2b^3+2c^3<3+a^2b+b^2c+c^2a
a, a,b,c>0. CMR:\(\dfrac{ab}{a+b+2c}+\dfrac{bc}{b+c+2a}+\dfrac{ac}{a+c+2b}\le\dfrac{a+b+c}{4}\)
b, a,b,c>0. CMR:\(\dfrac{ab}{a+3b+2c}+\dfrac{bc}{b+3c+2a}+\dfrac{ac}{c+3a+2b}\le\dfrac{a+b+c}{6}\)
Cho a,b,c>0 CMR
\(2\left(\frac{a}{b+2c}+\frac{b}{c+2a}+\frac{c}{a+2b}\right)\ge1+\frac{b}{b+2a}+\frac{c}{c+2b}+\frac{a}{a+2c}\)