Răspuns:
Explicație pas cu pas:
2^n+3*3^n+7 + 2^n+5*3^n+9 = 2^n+3*3^n+7*(1 + 2^2*3^2) = 37*2^n+3*3^n+7
√37*2^n+3*3^n+7/37 = √2^n+3*3^n+7
n = impar
n + 3 si n + 7 sunt numere pare
√2^n+3*3^n+7 ∈ N
