a)
\(\sqrt{2}.x-\sqrt{98}=0\)
\(\Leftrightarrow x-\sqrt{49}=0\)
\(\Leftrightarrow x-7=0\)
<=> x = 7
b)
\(\sqrt{2x}=\sqrt{8}\)
\(\Leftrightarrow\sqrt{x}=\sqrt{4}\)
<=> x = 4
c)
\(\sqrt{5}.x^2=\sqrt{20}\)
\(\Rightarrow x^2=\sqrt{4}\)
\(\Rightarrow x^2=2\)
\(\Rightarrow\left[\begin{array}{nghiempt}x=2\\x=-2\end{array}\right.\)
d)
\(2x^2-\sqrt{100}=0\)
\(\Leftrightarrow2x^2=10\)
\(\Leftrightarrow\left[\begin{array}{nghiempt}x=2\\x=-2\end{array}\right.\)
a/ \(\sqrt{2}x-\sqrt{98}=0\Leftrightarrow\sqrt{2}x=\sqrt{98}\Leftrightarrow x=7\)
b/ \(\sqrt{2x}=\sqrt{8}\) (ĐKXĐ : \(x\ge0\))
\(\Leftrightarrow2x=8\Leftrightarrow x=4\)
c/ \(\sqrt{5}x^2=\sqrt{20}\Leftrightarrow x^2=4\Leftrightarrow x=\pm2\)
d/ \(2x^2-\sqrt{100}=0\Leftrightarrow2x^2=10\Leftrightarrow x^2=5\Leftrightarrow x=\pm\sqrt{5}\)
2/ \(\sqrt{\frac{4}{\left(2-\sqrt{3}\right)^2}}+\sqrt{\frac{9}{\left(2+\sqrt{3}\right)^2}}=\frac{2}{2-\sqrt{3}}+\frac{3}{2+\sqrt{3}}\)
\(=\frac{2\left(2+\sqrt{3}\right)+3\left(2-\sqrt{3}\right)}{\left(2+\sqrt{3}\right)\left(2-\sqrt{3}\right)}=10-\sqrt{3}\)
2
\(\sqrt{\frac{4}{\left(2-\sqrt{3}\right)^2}}+\sqrt{\frac{9}{\left(2-\sqrt{3}\right)^2}}\)
\(=\sqrt{\left(\frac{2}{2-\sqrt{3}}\right)^2}+\sqrt{\left(\frac{3}{2-\sqrt{3}}\right)^2}\)
\(=\frac{2+3}{2+\sqrt{3}}=\frac{5}{2+\sqrt{3}}\)