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