Question

\(\sqrt{x^2+25}=13\)

Answer 1

\(\sqrt{x^2+25}=13\\ \Leftrightarrow x^2+25=169\\ \Leftrightarrow x^2=144\\ \Leftrightarrow\left[{}\begin{matrix}x=12\\x=-12\end{matrix}\right.\)

Answer 2

ĐKXĐ: mọi \(x\)

Ta có \(\sqrt{x^2+25}=13\)

\(\Leftrightarrow x^2+25=169\)

\(\Leftrightarrow x^2=144\)

\(\Leftrightarrow\left[{}\begin{matrix}x=\sqrt{144}\\x=-\sqrt{144}\end{matrix}\right.\) \(\Leftrightarrow\left[{}\begin{matrix}x=12\\x=-12\end{matrix}\right.\)