[tex]\it Gf\cap Gg= A(x,\ y) \Rightarrow \begin{cases} \it y=f(x) \Rightarrow y=3x-15\\ \\ \it y=g(x) \Rightarrow y=-8x+4\end{cases} \Rightarrow 3x-15=-8x+4 \Rightarrow \\ \\ \\ \Rightarrow 3x+8x=4+15 \Rightarrow 11x=19 \Rightarrow x=\dfrac{19}{11}\\ \\ \\ y=3x-15=3\cdot(\dfrac{19}{11})-15=\dfrac{57}{11}-15=\dfrac{57-165}{11}=-\dfrac{108}{11}\\ \\ \\ Gf\cap Gg=A(\dfrac{19}{11},\ -\dfrac{108}{11})[/tex]
