Hai số a,b thỏa mãn \(\left\{{}\begin{matrix}a,b>0\\\left(\sqrt{a}+1\right)\left(\sqrt{b}+1\right)\ge4\end{matrix}\right.\)
Chứng minh \(\dfrac{a^2}{b}+\dfrac{b^2}{a}\ge2\)
1. Cho \(\left\{{}\begin{matrix}x,y,z>0\\x+y+z=\dfrac{3}{4}\end{matrix}\right.\)
Tìm min \(C=\sqrt[3]{x+3y}+\sqrt[3]{y+3z}+\sqrt[3]{z+3x}\)
2. Với a,b,c là đô dài 3 cạnh 1 tam giác
Chứng minh: \(\sqrt[3]{a+b-c}+\sqrt[3]{b+c-a}+\sqrt[3]{c+a-b}\le\sqrt[3]{a}+\sqrt[3]{b}+\sqrt[3]{c}\)
giải các phương trình sau a)\(\left\{{}\begin{matrix}3\left(x-1\right)-\sqrt{1-2y}=1\\\left(x-1\right)+2\sqrt{1-2y}=5\end{matrix}\right.\)
b) \(\left\{{}\begin{matrix}\sqrt{x^2-2x+1}-3y=7\\2\left|x-1\right|-8y=1\end{matrix}\right.\)
c) \(\left\{{}\begin{matrix}2\left(x^2-x\right)+\sqrt{y-4}=0\\3\left(x^2-x\right)-2\sqrt{y-4}=-7\end{matrix}\right.\)
giải các hpt sau: a)\(\left\{{}\begin{matrix}4\sqrt{5}-y=3\sqrt{2}\\10x+\sqrt{2}y=-1\end{matrix}\right.\)
b) \(\left\{{}\begin{matrix}\dfrac{3x}{4}+\dfrac{2y}{5}=2,3\\x-\dfrac{3y}{5}=0,8\end{matrix}\right.\)
c) \(\left\{{}\begin{matrix}\left|x-1\right|-\dfrac{3}{\sqrt{y-2}}=-1\\2\left|1-x\right|+\dfrac{1}{\sqrt{y-2}}=5\end{matrix}\right.\)cíu zới
1,Ghpt:\(\left\{{}\begin{matrix}x^2+3y+1=\left(x+3\right)\sqrt{y^2+1}\\\sqrt{2x\left(x+y\right)^3}+y\sqrt{2\left(x^2+y^2\right)}=3\left(x^2+y^2\right)\end{matrix}\right.\)
2,Cho a,b,c,d∈Z tm:\(a^2+b^2+c^2=d^2\)
CMR:\(abc⋮4\) (xét chẵn lẻ)
a.\(\sqrt{28a^4}\)
b. A=\(\left(\dfrac{\sqrt{21}-\sqrt{7}}{\sqrt{3-1}}+\dfrac{\sqrt{10}-\sqrt{5}}{\sqrt{2}-1}\right)\)\(\div\)\(\dfrac{1}{\sqrt{7}-\sqrt{5}}\)
c.\(\left\{{}\begin{matrix}\dfrac{3}{2x}-y=6\\\dfrac{1}{x}+2y=-4\end{matrix}\right.\)
Ghpt:
a) \(\left\{{}\begin{matrix}\left(4x^2+1\right).x+\left(y-3\right)\sqrt{5-2y}=0\\4x^2+y^2+2\sqrt{3-4x}=7\end{matrix}\right.\)
b) \(\left\{{}\begin{matrix}x^2+y^2=5\\\sqrt{y-1}\left(x+y-1\right)=\left(y-2\right)\sqrt{x+y}\end{matrix}\right.\)
Giải hpt sau:
a)\(\left\{{}\begin{matrix}2\left(x^2-2x\right)+\sqrt{y+1}=0\\3\left(x^2-2x\right)-2\sqrt{y+1}+7=0\end{matrix}\right.\)
b)\(\left\{{}\begin{matrix}5\left|x-1\right|-3\left|y+2\right|=7\\2\sqrt{4x^2-8x+4}+5\sqrt{y^2+4y+4}=13\end{matrix}\right.\)
c)\(\left\{{}\begin{matrix}\dfrac{3x}{x+1}-\dfrac{2}{y+4}=4\\\dfrac{2x}{x+1}-\dfrac{5}{y+4}=9\end{matrix}\right.\)
d)\(\left\{{}\begin{matrix}\dfrac{x+1}{x-1}+\dfrac{3y}{y+2}=7\\\dfrac{2}{x-1}-\dfrac{5}{y+2}=4\end{matrix}\right.\)
a, rút gọn biểu thức: A= \(\sqrt{12}-\sqrt{27}+\sqrt{4+2\sqrt{3}}\)
b, giải phương trình: x2-2x-4=0
c, giải hệ phương trình: \(\left\{{}\begin{matrix}2x-y=5\\x+3y=-1\end{matrix}\right.\)