a,
`(x-5)(3-x)=0`
`->` \(\left[ \begin{array}{l}x-5=0\\3-x=0\end{array} \right.\)
`->` \(\left[ \begin{array}{l}x=5\\x=3\end{array} \right.\)
Vậy `x \in {3;5}`
b,
`(2x-8)(5-x)=0`
`->` \(\left[ \begin{array}{l}2x-8=0\\5-x=0\end{array} \right.\)
`->` \(\left[ \begin{array}{l}2x=8\\x=5\end{array} \right.\)
`->` \(\left[ \begin{array}{l}x=4\\x=5\end{array} \right.\)
Vậy `x \in {4;5}`
c,
`7x(2x-14)=0`
`->` \(\left[ \begin{array}{l}7x=0\\2x-14=0\end{array} \right.\)
`->` \(\left[ \begin{array}{l}x=0\\2x=14\end{array} \right.\)
`->` \(\left[ \begin{array}{l}x=0\\x=7\end{array} \right.\)
Vậy `x \in {0;7}`
d,
`(2x-4)(6-2x)=0`
`->` \(\left[ \begin{array}{l}2x-4=0\\6-2x=0\end{array} \right.\)
`->` \(\left[ \begin{array}{l}2x=4\\2x=6\end{array} \right.\)
`->` \(\left[ \begin{array}{l}x=2\\x=3\end{array} \right.\)
Vậy `x \in {2;3}`
