[tex]\it 13)\ \ f(x)=(m+2)x+5m+8\\ \\ A(m-2,\ m+1)\in Gf \Rightarrow f(m-2)=m+1 \Rightarrow (m+2)(m-2)+5m+8=\\ \\ =m+1 \Rightarrow m^2-4+5m+8-m-1=0 \Rightarrow m^2+4m+3=0 \Rightarrow \\ \\ \Rightarrow m^2+3m+m+3=0 \Rightarrow m(m+3)+(m+3)=0 \Rightarrow (m+3)(m+1)=0 \\ \\ m+3=0 \Rightarrow m_1=-3\\ \\ m+1=0 \Rightarrow m_2=-1[/tex]
