\(D=\frac{3}{2ab}+\frac{3}{a^2+b^2}+\frac{1}{2ab}=3\left(\frac{1}{2ab}+\frac{1}{a^2+b^2}\right)+\frac{1}{2ab}\)
\(\Rightarrow D\ge\frac{3.4}{2ab+a^2+b^2}+\frac{1}{\frac{2\left(a+b\right)^2}{4}}=\frac{12}{\left(a+b\right)^2}+\frac{2}{\left(a+b\right)^2}=14\)
\(\Rightarrow D_{min}=14\) khi \(a=b=\frac{1}{2}\)
Cho a,b,c>0 thỏa mãn \(a^2+b^2+c^2=1\) Tìm Min A=\(\frac{ab}{c}+\frac{bc}{a}+\frac{ca}{b}\)
1. a) \(\left\{{}\begin{matrix}x,y,z>0\\xyz=1\end{matrix}\right.\). Tìm max \(P=\frac{1}{\sqrt{x^5-x^2+3xy+6}}+\frac{1}{\sqrt{y^5-y^2+3yz+6}}+\frac{1}{\sqrt{z^5-z^2+zx+6}}\)
b) \(\left\{{}\begin{matrix}x,y,z>0\\xyz=8\end{matrix}\right.\). Min \(P=\frac{x^2}{\sqrt{\left(1+x^3\right)\left(1+y^3\right)}}+\frac{y^2}{\sqrt{\left(1+y^3\right)\left(1+z^3\right)}}+\frac{z^2}{\sqrt{\left(1+z^3\right)\left(1+x^3\right)}}\)
c) \(x,y,z>0.\) Min \(P=\sqrt{\frac{x^3}{x^3+\left(y+z\right)^3}}+\sqrt{\frac{y^3}{y^3+\left(z+x\right)^3}}+\sqrt{\frac{z^3}{z^3+\left(x+y\right)^3}}\)
d) \(a,b,c>0;a^2+b^2+c^2+abc=4.Cmr:2a+b+c\le\frac{9}{2}\)
e) \(\left\{{}\begin{matrix}a,b,c>0\\a+b+c=3\end{matrix}\right.\). Cmr: \(\frac{a}{b^3+ab}+\frac{b}{c^3+bc}+\frac{c}{a^3+ca}\ge\frac{3}{2}\)
f) \(\left\{{}\begin{matrix}a,b,c>0\\ab+bc+ca+abc=4\end{matrix}\right.\) Cmr: \(\sqrt{ab}+\sqrt{bc}+\sqrt{ca}\le3\)
g) \(\left\{{}\begin{matrix}a,b,c>0\\ab+bc+ca+abc=2\end{matrix}\right.\) Max : \(Q=\frac{a+1}{a^2+2a+2}+\frac{b+1}{b^2+2b+2}+\frac{c+1}{c^2+2c+2}\)
Cho 0<a,b,c<1 và ab+bc+ca=1 tìm \(P_{min}=\frac{a^2\left(1-2b\right)}{b}+\frac{b^2\left(1-2c\right)}{c}++\frac{c^2\left(1-2a\right)}{a}\)
1.Cho a, b dương thỏa mãn ab=1. tìm min của B=\(\frac{1}{a}+\frac{1}{b}+\frac{2}{a+b}\)
2. Tìm min của T=\(\frac{4a}{b+c-a}+\frac{9b}{a+c-b}+\frac{16c}{a+b-c}\)
1. Tìm số tự nhiên có 3 chữ số \(\overline{abc}=9\left(a^2+b^2+c^2\right)\)
2. giải hpt: \(\left\{{}\begin{matrix}x+y+z=5\\\frac{1}{x}+\frac{1}{y}+\frac{1}{z}=\frac{1}{5}\\y+z^2=1\end{matrix}\right.\)
3.a) \(\left\{{}\begin{matrix}a,b,c>0\\a+b+c=3\end{matrix}\right.\) Tìm Min \(P=a^2+b^2+c^2+\frac{ab+bc+ca}{a^2b+b^2c+c^2a}\)
b) Cho a,b,c > 0 thỏa mãn \(a^{2014}+b^{2014}+c^{2014}+d^{2014}=4\). Tìm Max \(P=a^2+b^2+c^2+d^2\)
Cho a,b,c>0 và \(a^2+b^2+c^2=3\)
Tìm \(P_{min}=\frac{a^2+1}{a}+\frac{b^2+1}{b}+\frac{c^2+1}{c}-\frac{1}{x+y+z}\)
1. cho \(0< a\le b\le c\) . Cmr: \(\frac{2a^2}{b^2+c^2}+\frac{2b^2}{c^2+a^2}+\frac{2c^2}{a^2+b^2}\le\frac{a^2}{b}+\frac{b^2}{c}+\frac{c^2}{a}\)
2. cho \(a,b,c\ge0\). cmr: \(a^2+b^2+c^2+3\sqrt[3]{\left(abc\right)^2}\ge2\left(ab+bc+ca\right)\)
3. \(a,b,c>0.\) Cmr: \(\sqrt{\left(a^2b+b^2c+c^2a\right)\left(ab^2+bc^2+ca^2\right)}\ge abc+\sqrt[3]{\left(a^3+abc\right)\left(b^3+abc\right)\left(c^3+abc\right)}\)
4. \(a,b,c>0\). Tìm Min \(P=\left(\frac{a}{a+b}\right)^4+\left(\frac{b}{b+c}\right)^4+\left(\frac{c}{c+a}\right)^4\)
Cho a,b,c>0 thỏa a+b+c=3. Tìm Max P \(\frac{2}{3+ab+bc+ca}+\frac{\sqrt{abc}}{6} +\sqrt[3]{\frac{abc}{\left(1+a\right)\left(1+b\right)\left(1+c\right)}}\)
Cho x,y,z>0 thỏa \(3x+y+z=x^2+y^2+z^2+2xy\) . Tìm Min P= \(\frac{20}{\sqrt{x+2}}+\frac{20}{\sqrt{y+2}}+x+y+z\)
Cho a, b > 0; a+b = 1. Tìm Min \(A=\left(a^2+\frac{1}{b^2}\right)\left(b^2+\frac{1}{a^2}\right)\)
