\(\left(x-1\right)\left(x+2\right)-x-2=0\\ \Rightarrow\left(x-1\right)\left(x+2\right)-\left(x+2\right)=0\\ \Rightarrow\left(x+2\right)\left(x-1-1\right)=0\\ \Rightarrow\left(x+2\right)\left(x-2\right)=0\\ \Rightarrow\left[{}\begin{matrix}x=-2\\x=2\end{matrix}\right.\)
\(\Leftrightarrow\left(x+2\right)\left(x-2\right)=0\)
\(\Leftrightarrow x\in\left\{2;-2\right\}\)
( x - 1 ) ( x + 2 ) - ( x + 2 ) = 0
( x + 2 ) ( x - 1 - 1 ) = 0
( x - 2 ) ( x + 2 ) = 0
TH1 : x - 2 = 0
=> x = 2
TH2: x + 2 = 0
=> x = -2
Vậy x = 2 hoặc x = -2
\(\left(x-1\right)\left(x+2\right)-x-2=0\\ x^2+2x-x-2-x-2=0\\ x^2-4=0\\ x^2=4\\ x=2\)
thankssss các bạn rất nhiều!!!!!!!!!!!!!
