(5 la puterea n+1 ×8 la puterea n + 2la puterea 3n+1 × 5 la puterea n) ÷(7× 4la puterea n
(5^n+1 × 8n + 2^3n+1 × 5^n)÷ ( 7×4^n)​
REPEDE VA ROG ​