Răspuns :
a, b ≤ 9, a ∈ IN*, b ∈ IN.
a + b = 4.
4 + 0, 3 + 1, 1 + 3, 2 + 2.
ab ∈ { 40, 31, 22, 13 }.
a + b = 4.
4 + 0, 3 + 1, 1 + 3, 2 + 2.
ab ∈ { 40, 31, 22, 13 }.