Question

X^2-5x-6=0

Answer 1

x²+x-6x-6=0
x(x+1)-6(x+1)=0
(x-6)(x+1)=0
x-6=0   <=>   x=6
hoặc x+1=0  <=>  x=-1

Answer 2

\(x^2-6x+x-6=0\)

\(x\left(x+1\right)-6\left(x+1\right)=0\)

\(\left(x-6\right)\left(x+1\right)=0\)

\(\left[{}\begin{matrix}x-6=0\\x+1=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=6\\x=-1\end{matrix}\right.\)