[tex] {2}^{n + 1} \times {5}^{n + 1} + 3 \times {2}^{n} \times {5}^{n + 1} - {2}^{n + 3} \times {5}^{n} = \\ (2 \times 5 + 3 \times 5 - {2}^{3} ) \times {2}^{n} \times {5}^{n} = \\ (10 + 15 - 8) \times {2}^{n} \times {5}^{n} = \\ 17 \times {2}^{n} \times {5}^{n} = \\ 17 \times {10}^{n} [/tex]
Sper că te-am ajutat! :-)
