Question

Tìm x   

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

Cảm ơn nhiều :))

Answer 1

\(\left(4-x\right)\left(x+7\right)=0\)

\(\Rightarrow\left[{}\begin{matrix}4-x=0\\x+7=0\end{matrix}\right.\)

\(\Rightarrow\left[{}\begin{matrix}x=4\\x=-7\end{matrix}\right.\)

Answer 2

`(4-x).(x+7)=0`

`<=>`\(\left[{}\begin{matrix}4-x=0\\x+7=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=4-0\\x=0-7\end{matrix}\right.\)

`<=>`\(\left[{}\begin{matrix}x=4\\x=-7\end{matrix}\right.\)

Vậy \(x\in\left\{4;-7\right\}\)

Answer 3

\(\left(4-x\right)\cdot\left(x+7\right)=0\)

`=>`\(\left[{}\begin{matrix}4-x=0\\x+7=0\end{matrix}\right.\)

`=>`\(\left[{}\begin{matrix}x=4-0\\x=0-7\end{matrix}\right.\)

`=>`\(\left[{}\begin{matrix}x=4\\x=-7\end{matrix}\right.\)