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c: \(\sqrt{3+\sqrt{8}}=\sqrt{2}+1\)
d: \(\sqrt{11+4\sqrt{6}}=2\sqrt{2}+3\)
e: \(\sqrt{14-6\sqrt{5}}=3-\sqrt{5}\)
a: \(\sqrt{2x+3}=5\)
\(\Leftrightarrow2x+3=25\)
hay x=11
b: \(\sqrt{\left(x-2\right)^2}=8\)
\(\Leftrightarrow\left|x-2\right|=8\)
\(\Leftrightarrow\left[{}\begin{matrix}x-2=8\\x-2=-8\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=10\\x=-6\end{matrix}\right.\)
a) \(\sqrt{3+2x}=5\left(đk:x\ge-\dfrac{3}{2}\right)\)
\(\Leftrightarrow3+2x=25\Leftrightarrow x=11\left(tm\right)\)
b) \(\sqrt{\left(x-2\right)^2}=8\)
\(\Leftrightarrow\left|x-2\right|=8\)
\(\Leftrightarrow\left[{}\begin{matrix}x-2=8\\x-2=-8\end{matrix}\right.\)\(\Leftrightarrow\left[{}\begin{matrix}x=10\\x=-6\end{matrix}\right.\)
c) \(đk:x\le3\)
\(\Leftrightarrow\sqrt{3-x}-3\sqrt{3-x}+5\sqrt{3-x}=6\)
\(\Leftrightarrow3\sqrt{3-x}=6\)
\(\Leftrightarrow\sqrt{3-x}=2\Leftrightarrow3-x=4\Leftrightarrow x=-1\left(tm\right)\)
d) \(đk:x\ge0\)
\(\Leftrightarrow4\sqrt{x}-6\sqrt{x}+4\sqrt{x}=5\)
\(\Leftrightarrow2\sqrt{x}=5\Leftrightarrow\sqrt{x}=\dfrac{5}{2}\Leftrightarrow x=\dfrac{25}{4}\left(tm\right)\)
e) \(đk:x\ge-5\)
\(\Leftrightarrow2\sqrt{x+5}-3\sqrt{x+5}+4\sqrt{x+5}=6\)
\(\Leftrightarrow3\sqrt{x+5}=6\Leftrightarrow\sqrt{x+5}=2\Leftrightarrow x+5=4\Leftrightarrow x=-1\left(tm\right)\)
f) \(đk:x\ge-2\)
\(\Leftrightarrow3\sqrt{x+2}-5\sqrt{x+2}+4\sqrt{x+2}=6\)
\(\Leftrightarrow2\sqrt{x+2}=6\Leftrightarrow\sqrt{x+2}=3\Leftrightarrow x+2=9\Leftrightarrow x=7\left(tm\right)\)
30 collection
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31 Do you go on social media every day?
32 I don't watch much TV, exept a bit on Youtube
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33 .........forget to give me those stamps
34 ........... fluent E speaker
35 ........ singing an E song?
36 ........ Lan is a poor student, she studies very well
12 A
13 C
14 C
15 C
16 B
14 A
18 C
19 A
20 D