[tex]\it a)\ x^2+3x+2=0\ \Rightarrow\ x^2+2x+x+2=0\ \Rightarrow\ x(x+2) +(x+2)=0 \Rightarrow\\ \\ \Rightarrow (x+2)(x+1)=0 \Rightarrow \begin{cases}\it x+2=0 \Rightarrow x_1=-2\\ \\ \it x+1=0 \Rightarrow x_2=-1\end{cases}[/tex]
[tex]\it b)\ x^2+7x-8=0 \Rightarrow x^2-x+8x-8=0 \Rightarrow x(x-1)+8(x-1)=0 \Rightarrow \\ \\ \Rightarrow (x-1)(x+8)=0 \Rightarrow \begin{cases}\it x+8=0 \Rightarrow x_1=-8\\ \\ \it x-1=0 \Rightarrow x_2=1\end{cases}[/tex]
