Răspuns :
A(1,2) => f(1)=2
5×1-3=2
5-3=2
2=2=> A € Gf
B(-2,7)=> f(-2)=7
5×(-2)-3=7
-10-3=7
-13=7=> B nu apartine Gf
C(0,4 ,1)=> f(0,4)=1
5×0,4-3=1
2-3=1
-1=1=> C nu apartine Gf
5×1-3=2
5-3=2
2=2=> A € Gf
B(-2,7)=> f(-2)=7
5×(-2)-3=7
-10-3=7
-13=7=> B nu apartine Gf
C(0,4 ,1)=> f(0,4)=1
5×0,4-3=1
2-3=1
-1=1=> C nu apartine Gf
Ca un punct de coordonate (x, y )sa apartina graficului atunci fiecare punct trebuie sa verifice functia, adica
f (1)=2 ?
f (1)=5×1-3=2? Adevarat A apartine Gf
f (-2)=7?
f (-2)=5×-2-3=7
f (-2)=-10-3=7 Adevarat B apartine Gf
f (0.4)=1?
f (0.4)=5×0.4+3=1
f (0.4)=1 fals C nu apartine Gf
f (1)=2 ?
f (1)=5×1-3=2? Adevarat A apartine Gf
f (-2)=7?
f (-2)=5×-2-3=7
f (-2)=-10-3=7 Adevarat B apartine Gf
f (0.4)=1?
f (0.4)=5×0.4+3=1
f (0.4)=1 fals C nu apartine Gf