1)
x_(C)=(2+4)/2=3
y_(C)=(3+(-5))/2=-1
z_(C)=(-2+6)/2=2
(3;-1;2)
2)
x_(C)=(2+([red]1/2[/red])*4)/(1+([red]1/2[/red]))=
y_(C)=(3+([red]1/2[/red])*(-5))/(1+([red]1/2[/red]))=
z_(C)=(-2+([red]1/2[/red])*6)/(1+([red]1/2[/red]))=
3)
x_(C)=(2+[red]2[/red]*4)/1+[red]2[/red])=
y_(C)=(3+[red]2[/red]*(-5))/(1+[red]2[/red])=
z_(C)=(-2+[red]2[/red]*6)/(1+[red]2[/red])=