Răspuns:
A(1 ;2) ; B (7;17) ; C (3 ; 7) ; D(5 ; 12)
Explicație pas cu pas:
f : R --> R , f(x) = 5x/2 - 0,5 = 5x/2 - 1/2 = (5x-1)/2
A (1 ;2) ∈Gf <=> f(1) = 2 <=> (5x-1)/2 = 2 => (5·1-1)/2 = 4/2 = 2 => A(1 ;2) ∈Gf
B (7;17) ∈Gf <=>f(7) = 17 => (5·7-1)/2 = 34/2 = 17 => B (7;17) ∈ Gf
f(3) = (5·3-1)/2 = 14/2 = 7 => C (3 ; 7)
f(4) = (5·4-1)/2 = 19/2 ∉Z
f(5) = (5·5-1)/2 = 24/2 = 12 => D(5 ; 12)
f(6) = (5·6-1)/2 = 29/2 ∉Z
