`a)x^2-5x=0`
`=>x(x-5)=0`
`=>`\(\left[ \begin{array}{l}x=0\\x-5=0\end{array} \right.\)
`=>`\(\left[ \begin{array}{l}x=0\\x=5\end{array} \right.\)
Vậy `x={0;5}`
`b)x^2-7x=0`
`=>x(x-7)=0`
`=>`\(\left[ \begin{array}{l}x=0\\x-7=0\end{array} \right.\)
`=>`\(\left[ \begin{array}{l}x=0\\x=7\end{array} \right.\)
Vậy `x={0;7}.`
