a)
[tex]A(x,\ y)\in Gf\cap Gg \Rightarrow f(x)=g(x) \Rightarrow 2x+4=x+3 \Rightarrow 2x-x=3-4 \Rightarrow x=-1\\ \\y= f(-1)=2\cdot(-1)+4=-2+4=2,\ Deci,\ A(-1.\ 2)\in Gf\cap Gg[/tex]
b)
[tex]\it f(2)=2\cdot2+4=4+4=8[/tex]
c)
[tex]\it P(-1,\ -1)\in Gf\iff f(-1)=-1 \iff -2+4=-1 \iff 2=-1\ (F)[/tex]
d)
[tex]\it M(a,\ 6)\in Gf \Rightarrow f(a)=-6 \Rightarrow 2a+4=6\bigg|_{-4} \Rightarrow 2a=2 \Rightarrow a=1[/tex]
e)
[tex]B(x,\ 2x)\in Gf \Rightarrow f(x)=2x \Rightarrow 2x+4=2x \Rightarrow 2x-2x=-4 \Rightarrow \\ \\ \Rightarrow 0x=-4 \Rightarrow x\in \O\ .\ \ \ Deci,\ nu\ exist\breve a\ un\ astfel\ de\ num\breve ar[/tex]