Răspuns:
f(x)=ax+b
f(1)=a+b=2
f(-2)=-2a=7
a=-7/2
-7/2+b=2
-7+2b=4
2b=4+7
2b=11
b=11/2
f(x)=-7/2x+11/2
b. f(x)=ax+b
f(2/5)=0 si f(0)=2
f(2/5)=2/5a+b=0
f(0)=b=2
2/5a+2=0
2a+10=0
2a=-10
a=-10:2
a=-5
f(x)=-5x+2
c.
A(0,3) ∈ Gf si B(1,7) ∈ Gf
f(0)=3
f(1)=7
f(x)=ax+b
f(0)=b=3
f(1)=a+b=7
a+3=7
a=7-3=4
f(x)=4x+3
d.
A(2,4) ∈ Gf si B(6,12) ∈ Gf
f(2)=4
f(6)=12
f(x)=ax+b
f(2)=2a+b=4
b=4-2a
f(6)=6a+b=12
6a+4-2a=12
4a+4=12 /:4
a+1=3
a=3-1=2
b=4-2a
b=4-2×2=4-4=0
f(x)=2x
