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Cho a,b,c >0 .CMR:
\(\dfrac{a}{a+b}+\dfrac{b}{b+c}+\dfrac{c}{c+a}< \sqrt{\dfrac{a}{b+c}}+\sqrt{\dfrac{b}{c+a}}+\sqrt{\dfrac{c}{a+b}}\)
a) Giải \(\left\{{}\begin{matrix}x\sqrt{y}+y\sqrt{x}=30\\x\sqrt{x}+y\sqrt{y}=35\end{matrix}\right.\)
b) Cho 0 < a < b < c < d. Chứng minh \(\left(b+c\right)\left(\dfrac{1}{b}+\dfrac{1}{c}\right)< \dfrac{\left(a+d\right)^2}{ad}\)
Cho a;b;c >0.
CMR : \(\dfrac{a^2}{b^2+c^2}+\dfrac{b^2}{a^2+c^2}+\dfrac{c^2}{a^2+b^2}\ge\dfrac{a}{b+c}+\dfrac{b}{a+c}+\dfrac{c}{a+b}\)
Cho A = \(\dfrac{b^2}{a+b}+\dfrac{c^2}{b+c}+\dfrac{a^2}{a+c}\); B= \(\dfrac{a^2}{a+b}+\dfrac{b^2}{b+c}+\dfrac{c^2}{a+c}\). CMR A = B
Cho \(\dfrac{a-c}{b+c}+\dfrac{b-c}{c+a}+\dfrac{c-b}{a+b}=1\) Cmr: \(\dfrac{a+b}{b+c}+\dfrac{b+c}{c+a}+\dfrac{c+a}{a+b}=4\)
Cho a,b,c là 3 số khác 0 thỏa mãn \(\dfrac{1}{a}+\dfrac{1}{b}+\dfrac{1}{c}=0\).CMR \(\dfrac{1}{a^3}+\dfrac{1}{b^3}+\dfrac{1}{c^3}=\dfrac{3}{abc}\)
Tìm tập xác định và rút gọn \(A=\dfrac{3\left(\sqrt{ab}-b\right)}{a-b}+\dfrac{\left(\sqrt{a}-\sqrt{b}\right)^3+2a\sqrt{a}+b\sqrt{b}}{a\sqrt{a}+b\sqrt{b}}\)
Cho \(\dfrac{a}{b+c}+\dfrac{b}{c+a}+\dfrac{c}{a+b}=1\)
C/m \(\dfrac{a^2}{b+c}+\dfrac{b^2}{c+a}+\dfrac{c^2}{a+b}=0\)
\(A=\left(\dfrac{x-5\sqrt{x}}{x-25}-1\right):\left(\dfrac{25-x}{x+2\sqrt{x}-15}-\dfrac{\sqrt{x}+3}{\sqrt{x}+5}+\dfrac{\sqrt{x}-5}{\sqrt{x}+3}\right)\)
\(B=\left(\dfrac{2+x}{2-x}-\dfrac{4x^2}{x^2-4}-\dfrac{2-x}{x+2}\right):\dfrac{x^2-3x}{2x^2-x^3}\)
a) Rút gọn A & B
b) Tìm x để B > 0
c) Tính B khi \(\left|1-x\right|=0\)