ex 3 punctul c va rog

Daca x<0,
f○f = f(f(x)) = f(2x + 3) = 2(2x + 3) + 3 = 4x + 6 + 3 = 4x + 9
Daca x≥0,
f○f = f(f(x)) = f(5) = 5