Câu 2.
a) \(\sqrt{\left(2x+3\right)^2}=4\)
\(\Rightarrow\left|2x+3\right|=4\\ \Rightarrow\left[{}\begin{matrix}2x+3=-4\\2x+3=4\end{matrix}\right.\\ \Rightarrow\left[{}\begin{matrix}x=-3,5\\x=0,5\end{matrix}\right.\)
b) \(\sqrt{9x}-5\sqrt{x}=6-4\sqrt{x}\\ \Rightarrow\sqrt{9}\sqrt{x}-5\sqrt{x}+4\sqrt{x}=6\\ \Rightarrow3\sqrt{x}-5\sqrt{x}+4\sqrt{x}=6\\ \Rightarrow2\sqrt{x}=6\\ \Rightarrow\sqrt{x}=3\\ \Rightarrow x=9\)
Câu 1:
a) \(\sqrt{18}-2\sqrt{50}+3\sqrt{8}=3\sqrt{2}-2.5\sqrt{2}+3.2\sqrt{2}=3\sqrt{2}-10\sqrt{2}+6\sqrt{2}=-\sqrt{2}\)
b) \(\left(\sqrt{7}-\sqrt{3}\right)^2+\sqrt{84}=7-2\sqrt{21}+3+2\sqrt{21}=7+3=10\)
c) mờ quá không nhìn thấy
1c/
\(\left(\frac{6-2\sqrt{2}}{3-\sqrt{2}}-\frac{5}{\sqrt{5}}\right):\frac{1}{2-\sqrt{5}}=\left[\frac{2(3-\sqrt{2})}{3-\sqrt{2}}-\sqrt{5}\right].(2-\sqrt{5})\)
\(=(2-\sqrt{5})(2-\sqrt{5})=9-4\sqrt{5}\)
