a) \(\sqrt{4x+20}+\sqrt{x+5}-\dfrac{1}{3}\sqrt{9x+45}=4\) (ĐK: \(x\ge-5\))
\(\Leftrightarrow\sqrt{4\left(x+5\right)}+\sqrt{x+5}-\dfrac{1}{3}\sqrt{9\left(x+5\right)}=4\)
\(\Leftrightarrow2\sqrt{x+5}+\sqrt{x+5}-\dfrac{1}{3}\cdot3\sqrt{x+5}=4\)
\(\Leftrightarrow3\sqrt{x+5}-\sqrt{x+5}=4\)
\(\Leftrightarrow2\sqrt{x+5}=4\)
\(\Leftrightarrow\sqrt{x+5}=2\)
\(\Leftrightarrow x+5=4\)
\(\Leftrightarrow x=-1\left(tm\right)\)
Vậy: ...
b) \(\dfrac{2\sqrt{x}-7}{3}+\sqrt{x}-\dfrac{3\sqrt{x}-5}{2}=1\) (ĐK: \(x\ge0\) )
\(\Leftrightarrow\dfrac{2\left(2\sqrt{x}-7\right)}{6}+\dfrac{6\sqrt{x}}{6}-\dfrac{3\left(3\sqrt{x}-5\right)}{6}=\dfrac{6}{6}\)
\(\Leftrightarrow4\sqrt{x}-14+6\sqrt{x}-9\sqrt{x}+15=6\)
\(\Leftrightarrow\sqrt{x}+1=6\)
\(\Leftrightarrow\sqrt{x}=5\)
\(\Leftrightarrow x=5^2\)
\(\Leftrightarrow x=25\left(tm\right)\)
Vậy: ...
