Question

Giải phương trình

a)\(\sqrt{49x^2-14x+1}=6\)

b)\(24\sqrt{2}.x-3\sqrt{18}=7\sqrt{2}-\sqrt{32}\)

c)\(\sqrt{15}.x^2-\sqrt{240}=0\)

d)\(\dfrac{x^2}{\sqrt{7}}-\sqrt{63}=0\)

Answer 1

a, \(\sqrt{\left(7x-1\right)^2}=6\Leftrightarrow\left[{}\begin{matrix}7x-1=6\\7x-1=-6\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=1\\x=-\dfrac{5}{7}\end{matrix}\right.\)

b, \(24\sqrt{2}x-9\sqrt{2}=7\sqrt{2}-4\sqrt{2}\)

\(\Leftrightarrow24\sqrt{2}x=12\sqrt{2}\Leftrightarrow x=\dfrac{1}{2}\)

c, \(\sqrt{15}\left(x^2-4\right)=0\Leftrightarrow x=2;x=-2\)

d, \(x^2-\sqrt{7.63}=0\Leftrightarrow x^2=21\Leftrightarrow x=\pm\sqrt{21}\)