Đáp án:
$\begin{array}{l}
Dkxd:{x^2} - 5x \ne 0 \Rightarrow x\left( {x - 5} \right) \ne 0 \Rightarrow x \ne 0;x \ne 5\\
\frac{{{x^2} - 10x + 25}}{{{x^2} - 5x}} = 2,5\\
\Rightarrow \frac{{{{\left( {x - 5} \right)}^2}}}{{x\left( {x - 5} \right)}} = 2,5\\
\Rightarrow \frac{{x - 5}}{x} = 2,5\\
\Rightarrow x - 5 = 2,5x\\
\Rightarrow 1,5x = 5\\
\Rightarrow x = \frac{{10}}{3}\left( {tmdk} \right)\\
Vậy\,x = \frac{{10}}{3}
\end{array}$