x = 2 hoặc = 6
Cách làm:
x2 - 8x + 12 = 0
x2 - 6x - 2x + 12 = 0
( x2 - 6x ) - ( 6x - 12 ) = 0
x . ( x - 2 ) - 6 . ( x - 2 ) = 0
( x - 2 ) . ( x - 6 ) = 0
\(\Rightarrow\hept{\begin{cases}x-2=0\\x-6=0\end{cases}}\hept{\begin{cases}x=2\\x=6\end{cases}}\)
x2-8x+12=0
<=> x2-6x-2x+12=0
<=> (x2-2x)-(6x-12)=0
<=> x.(x-2)-6.(x-2)=0
<=> (x-2)(x-6)=0
<=>\(\orbr{\begin{cases}x-2=0\\x-6=0\end{cases}}\Leftrightarrow\orbr{\begin{cases}x=2\\x=6\end{cases}}\)
\(=x^2-2x-6x+12\)
\(=x\left(x-2\right)-6\left(x-2\right)\)
\(=\left(x-2\right)\left(x-6\right)\)
Cả 2 bn đều làm đúng rồi k cho mk nha bn