Giải phương trình sau : x^2 5x + 6 = 0

* Hướng dẫn giải

$\begin{array}{l}{x}^2+5x+6=0\\ \iff x^2+2x+3x+6=0\\ \iff x\left(x+2\right)+3\left(x+2\right)=0\\ \iff \left(x+2\right)\left(x+3\right)=0\\ \iff \left[\begin{array}{l}x+2=0\\ x+3=0\end{array}\right.\iff \left[\begin{array}{l}x=-2\\ x=-3\end{array}\right.\\ S=\left\{-2;-3\right\}\end{array}$