Question

tìm số nguyên x biết :

(5- x) .(x +7)=0

Answer 1

\(\left(5-x\right)\left(x+7\right)=0\\ \Rightarrow\left[{}\begin{matrix}5-x=0\\x+7=0\end{matrix}\right.\\ \Rightarrow\left[{}\begin{matrix}x=5\\x=-7\end{matrix}\right.\)

Answer 2

\(\left[{}\begin{matrix}5-x=0\\x+7=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=5\\x=-7\end{matrix}\right.\)