Răspuns :
3ˣ⁺¹ ≤ 81 = 3⁴
x+1 ≤ 4
x ≤ 3 ⇒ x = {0; 1; 2; 3}
Verificare: 3⁰⁺¹ = 3¹ ≤ 81 (A)
3¹⁺¹ = 3²≤ 81 (A)
3²⁺¹ = 3³≤ 81 (A)
3³⁺¹ = 3⁴= 81 = 3⁴ (A)
3ˣ⁺¹ ≤ 81 = 3⁴
x+1 ≤ 4
x ≤ 3 ⇒ x = {0; 1; 2; 3}
Verificare: 3⁰⁺¹ = 3¹ ≤ 81 (A)
3¹⁺¹ = 3²≤ 81 (A)
3²⁺¹ = 3³≤ 81 (A)
3³⁺¹ = 3⁴= 81 = 3⁴ (A)