a/ ĐKXĐ: \(x>3\)
\(\Leftrightarrow\sqrt{2\left(x^2-16\right)}+x-3=7-x\)
\(\Leftrightarrow\sqrt{2\left(x^2-16\right)}=10-2x\) (\(x\le5\))
\(\Leftrightarrow2\left(x^2-16\right)=\left(10-2x\right)^2\)
\(\Leftrightarrow x^2-20x+66=0\)
b/ ĐKXĐ: \(x>0\)
\(\Leftrightarrow\sqrt{\frac{\left(x+1\right)\left(x^2-x+1\right)}{x}}-\sqrt{x+1}-\left(\sqrt{x^2-x+1}-\sqrt{x}\right)=0\)
\(\Leftrightarrow\sqrt{\frac{x+1}{x}}\left(\sqrt{x^2-x+1}-\sqrt{x}\right)-\left(\sqrt{x^2-x+1}-\sqrt{x}\right)=0\)
\(\Leftrightarrow\left(\sqrt{\frac{x+1}{x}}-1\right)\left(\sqrt{x^2-x+1}-\sqrt{x}\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}\sqrt{\frac{x+1}{x}}=1\\\sqrt{x^2-x+1}=\sqrt{x}\end{matrix}\right.\) \(\Leftrightarrow\left[{}\begin{matrix}\frac{x+1}{x}=1\\x^2-x+1=x\end{matrix}\right.\)
c/ĐKXĐ: \(x\ge-1\)
\(\Leftrightarrow\sqrt{\frac{\left(x+1\right)\left(x^2-x+1\right)}{\sqrt{x+3}}}+\sqrt{x+1}-\left(\sqrt{x^2+x+1}+\sqrt{x+3}\right)=0\)
\(\Leftrightarrow\sqrt{\frac{x+1}{x+3}}\left(\sqrt{x^2-x+1}+\sqrt{x+3}\right)-\left(\sqrt{x^2-x+1}+\sqrt{x+3}\right)=0\)
\(\Leftrightarrow\left(\sqrt{\frac{x+1}{x+3}}-1\right)\left(\sqrt{x^2-x+1}+\sqrt{x+3}\right)=0\)
\(\Leftrightarrow\sqrt{\frac{x+1}{x+3}}=1\Leftrightarrow x+1=x+3\)
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