Question

Tìm x:

(x-1).(x+2)-x-2+0

Answer 1

\(\left(x-1\right)\left(x+2\right)-x-2=0\)

\(\Leftrightarrow\left(x-1\right)\left(x+2\right)-\left(x+2\right)=0\)

\(\Leftrightarrow\left(x+2\right)\left(x-1-1\right)=0\)

\(\Leftrightarrow\left(x+2\right)\left(x-2\right)=0\)

\(\Leftrightarrow\left[{}\begin{matrix}x=2\\x=-2\end{matrix}\right.\)

Answer 2

=0 hay +0 bn
nếu (x-1).(x+2)-x-2 =0

x^2 + 2x -x-2-x-2=0

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

x^2-4 =0 => x^2 = 4 =>x = 2 hoặc -2