\(10x\left(x-5\right)-x+5=0\)
\(\Leftrightarrow10x\left(x-5\right)-\left(x-5\right)=0\)
\(\Leftrightarrow\left(x-5\right)\left(10x-1\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x=5\\x=\dfrac{1}{10}\end{matrix}\right.\)
b/ \(x\left(x^2-2x+5\right)=x^3-2x^2+5x\)