Question

giá trị x thỏa mãn x^2+7x+12=0

Answer 1

\(x^2+7x+12=0\)

\(\Leftrightarrow x^2+4x+3x+12=0\)

\(\Leftrightarrow\left(x+3\right)\left(x+4\right)=0\)

\(\Leftrightarrow\left[\begin{matrix}x=-3\\x=-4\end{matrix}\right.\)

Vậy .............

Answer 2

\(x^2+7x+12=0\)

\(x^2+3x+4x+12=0\)

\(x\left(x+3\right)+4\left(x+3\right)=0\)

\(\left(x+3\right)\left(x+4\right)=0\)

\(\Leftrightarrow\left[\begin{matrix}x+3=0\\x+4=0\end{matrix}\right.\Leftrightarrow\left[\begin{matrix}x=-3\\x=-4\end{matrix}\right.\)