\(\Leftrightarrow\)x^2-7x+x-7=0
\(\Leftrightarrow\)x^2-6x-7=0
\(\Leftrightarrow\)(x^2-7x)+(x-7)=0
\(\Leftrightarrow\)x(x-7)+(x-7)=0
\(\Leftrightarrow\)(x-7)(x+1)=0
\(\Rightarrow\)\(\left\{{}\begin{matrix}x-7=0\\x+1=0\end{matrix}\right.\)\(\Rightarrow x=7;-1\)
Vậy...
\(x\left(x-7\right)+\left(x-7\right)\)=0
\(\Rightarrow\left(x-7\right)\left(x+1\right)=0\)
\(\Rightarrow\)\(\left[{}\begin{matrix}x-7=0\\x+1=0\end{matrix}\right.\)
\(\Rightarrow\left[{}\begin{matrix}x=7\\x=-1\end{matrix}\right.\)
Vậy x = 7 và x = -1
CHÚC BẠN HỌC TỐT =))
