[tex]2 {}^{n + 1} \times 3 {}^{n} + 5 \times 6 {}^{n} = \\ = (2 \times 3) {}^{n} \times2 {}^{1} + 5 \times 6 {}^{n} = \\ = 6 {}^{n} \times 2 + 5 \times 6 {}^{n} = \\ = 6 {}^{n} (2 + 5) = \\ = 6 {}^{n} \times 7[/tex]
divizibil cu 7
Sper ca te-am ajutat!