[tex]\it Fie\ Gf\cap Gg=A(x,\ y) \Rightarrow \begin{cases} \it A(x,\ y)\in Gf \Rightarrow y=f(x) \Rightarrow y=x+1\ \ \ \ \ \ (1)\\ \\ \it A(x,\ y)\in Gg \Rightarrow y=g(x) \Rightarrow y=3x-7\ \ \ \ \ \ (2)\end{cases} \\ \\ \\ (1),\ (2) \Rightarrow 3x-7=x+1 \Rightarrow 3x-x=1+7 \Rightarrow 2x=8|_{:2} \Rightarrow x=4\\ \\ x=4\ \stackrel{(1)}{\Longrightarrow}\ y=4+1 \Rightarrow y=5[/tex]
[tex]\it\ Deci,\ \ Gf\cap Gg=A(4,\ 5)[/tex]
