Đáp án:

`x(x-5)=6`

`⇒x²-5x-6=0`

`⇒x²-6x+x-6=0`

`⇒x(x-6)+(x-6)=0`

`⇒(x-6)(x+1)=0`

`⇒`\(\left[ \begin{array}{l}x-6=0\\x+1=0\end{array} \right.\) 

`⇒`\(\left[ \begin{array}{l}x=6\\x=-1\end{array} \right.\) 

             Vậy `x∈{6;-1}`