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e: \(=\left|3-\sqrt{2}\right|=3-\sqrt{2}\)
h: \(=3-\sqrt{2}+3+\sqrt{2}=6\)
g: \(=\left|0.1-\sqrt{0.1}\right|=0.1-\sqrt{0.1}\)
i: \(=\left|2\sqrt{2}-3\right|=3-2\sqrt{2}\)
c: \(=\left|2+5\right|=7\)
o: \(=5-2\sqrt{6}-5-2\sqrt{6}=-4\sqrt{6}\)
n: \(=4-2\sqrt{3}+4+2\sqrt{3}=8\)
m: \(=7+2\sqrt{10}-7-2\sqrt{10}=0\)
![](https://rs.olm.vn/images/avt/0.png?1311)
\(\frac{3\sqrt{10}+\sqrt{20}-3\sqrt{6}-\sqrt{12}}{\sqrt{5}-\sqrt{3}}\)
\(=\frac{3\sqrt{10}+2\sqrt{5}-3\sqrt{6}-2\sqrt{3}}{\sqrt{5}-\sqrt{3}}\)
\(=\frac{\left(3\sqrt{10}-3\sqrt{6}\right)+\left(2\sqrt{5}-2\sqrt{3}\right)}{\sqrt{5}-\sqrt{3}}\)
\(=\frac{3\sqrt{2}\left(\sqrt{5}-\sqrt{3}\right)+2\left(\sqrt{5}-\sqrt{3}\right)}{\sqrt{5}-\sqrt{3}}\)
\(=3\sqrt{2}+2\)
![](https://rs.olm.vn/images/avt/0.png?1311)
a) \(\sqrt{\left(\sqrt{3}-2\right)^2}=\sqrt{3}-2\)
b) \(\sqrt{\left(2\sqrt{2}-3\right)^2}=2\sqrt{2}-3\)
a)\(\sqrt{\left(\sqrt{3}-2\right)^2}=\sqrt{\left(2-\sqrt{3}\right)^2}=2-\sqrt{3}\) (vì 2>\(√3\))
b) \(\sqrt{\left(2\sqrt{2}-3\right)^2}=\sqrt{\left(3-2\sqrt{2}\right)^2}=3-2\sqrt{2}\) (vì 3>\(2\sqrt{2}\))
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\(Q=\sqrt{1+2006^2+\left(\dfrac{2006}{2007}\right)^2}+\dfrac{2006}{2007}\)
=\(1+2006+\dfrac{2006}{2007}+\dfrac{2006}{2007}\)
=\(2007+\dfrac{4012}{2007}\)
=\(\dfrac{2007^2}{2007}+4012\)
=\(\dfrac{4028049}{2007}+\dfrac{4012}{2007}\)
=\(\dfrac{4032061}{2007}\)
\(Q=\sqrt{1+2006^2+\dfrac{2006^2}{2007^2}}+\dfrac{2006}{2007}\)
\(=1+2006+\dfrac{2006}{2007}+\dfrac{2006}{2007}\)
\(=\dfrac{4032061}{2007}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
a: Theo đề, ta có:
BH+CH=25(cm)
hay BH=25-CH
Ta có: \(AH^2=HB\cdot HC\)
\(\Leftrightarrow HC\left(HC-25\right)=-144\)
\(\Leftrightarrow HC=16\left(cm\right)\)
\(\Leftrightarrow HB=9\left(cm\right)\)
\(\Leftrightarrow\left\{{}\begin{matrix}AB=\sqrt{9\cdot25}=15\left(cm\right)\\AC=\sqrt{16\cdot25}=20\left(cm\right)\end{matrix}\right.\)
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Bài 1:
Xét tứ giác ABDC có \(\widehat{A}+\widehat{D}=180^0\)
nên ABDC là tứ giác nội tiếp
![](https://rs.olm.vn/images/avt/0.png?1311)
a: Đặt 1/x=a
1/(y-2)=b
Hệ phương trình trở thành:
\(\left\{{}\begin{matrix}2a+3b=4\\4a+b=1\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}4a+6b=8\\4a+b=1\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}5b=7\\4a+b=1\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}b=\dfrac{7}{5}\\a=-\dfrac{1}{10}\end{matrix}\right.\)
\(\Leftrightarrow\left\{{}\begin{matrix}\dfrac{1}{x}=\dfrac{-1}{10}\\\dfrac{1}{y-2}=\dfrac{7}{5}\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x=-10\\y-2=\dfrac{5}{7}\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x=-10\\y=\dfrac{19}{7}\end{matrix}\right.\)
b: \(\Leftrightarrow\left\{{}\begin{matrix}-\dfrac{2}{y}=0\\\dfrac{2}{x+1}+\dfrac{3}{y}=-1\end{matrix}\right.\)
=>Hệ phương trình vô nghiệm
a) \(\left\{{}\begin{matrix}\dfrac{2}{x}+\dfrac{3}{y-2}=4.\\\dfrac{4}{x}+\dfrac{1}{y-2}=1.\end{matrix}\right.\) \(ĐK:x\ne0;y\ne2.\)
Đặt \(\dfrac{1}{x}=a;\dfrac{1}{y-2}=b\left(a;b\ne0\right).\)
\(\Rightarrow\left\{{}\begin{matrix}2a+3b=4.\\4a+b=1.\end{matrix}\right.\) \(\Leftrightarrow\left\{{}\begin{matrix}a=\dfrac{-1}{10}.\\b=\dfrac{7}{5}.\end{matrix}\right.\) (TM).
\(\Rightarrow\left\{{}\begin{matrix}\dfrac{1}{x}=\dfrac{-1}{10}.\\\dfrac{1}{y-2}=\dfrac{7}{5}.\end{matrix}\right.\) \(\Leftrightarrow\left\{{}\begin{matrix}x=-10\left(TM\right).\\y=\dfrac{19}{7}\left(TM\right).\end{matrix}\right.\)
Vậy hệ phương trình có nghiệm \(\left(x;y\right)=\left(-10;\dfrac{19}{7}\right).\)
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Bài 1:
a: \(\dfrac{13\sqrt{2}-4\sqrt{6}}{24-4\sqrt{3}}=\dfrac{\sqrt{2}\left(13-4\sqrt{3}\right)}{4\sqrt{3}\left(2\sqrt{3}-1\right)}=\dfrac{\sqrt{2}\left(2\sqrt{3}-1\right)}{4\sqrt{3}}=\dfrac{\sqrt{6}\left(2\sqrt{3}-1\right)}{12}\)
b: \(\dfrac{\sqrt{3-2\sqrt{2}}}{\sqrt{17-12\sqrt{2}}}=\dfrac{\sqrt{2}-1}{3-2\sqrt{2}}=\sqrt{2}+1\)
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\(tana=\dfrac{\sqrt{5}}{3}\)
=>\(\dfrac{sina}{cosa}=\dfrac{\sqrt{5}}{3}\)
=>\(sina=cosa\cdot\dfrac{\sqrt{5}}{3}\)
\(B=\dfrac{2\cdot cosa+\dfrac{\sqrt{5}}{3}\cdot cosa}{5\cdot cosa-3\cdot\dfrac{\sqrt{5}}{3}\cdot cosa}=\left(2+\dfrac{\sqrt{5}}{3}\right):\left(5-\sqrt{5}\right)\)
\(=\dfrac{6+\sqrt{5}}{3\left(5-\sqrt{5}\right)}=\dfrac{35+11\sqrt{5}}{40}\)
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