\( n \) désignant un entier naturel non nul, on considère l'ensemble \( E_{n} \) des mots de \( n \) lettres que l'on peut former à l'aide des lettres a, b et c uniquement et ne contenant pas deux lettres consécutives identiques. On note \( F_{n} \) la partie de \( E_{n} \) constituée par les mots qui commencent et se terminent par deux lettres différentes. On pose \( \alpha_{n}=\operatorname{card}\left(E_{n}\right) \) et \( \beta_{n}=\operatorname{card}\left(F_{n}\right) \). 1. Déterminer \( \alpha_{n} \) en fonction de \( n \).

uchun 150 masala berildi. O'quvchining yechgan masalalari yechmaganiga qaraganda 4 marta ortiq bo'lsa, u nechta masala yechgan?

What would the effect of contractionary monetary policy be on the aggregate level of income and spending? A An increase in the aggregate level of income and spending. B A decrease in the aggregate level of income and spending. C An increase in the aggregate level of income and a decrease in the aggregate level of spending. D A decrease in the aggregate level of income and an increase in the aggregate level of spending.

Using practical examples, discuss the barriers to effective listening.

2. \( 2^{2}-2^{-2}+2^{1} \)

\( ( 1 , \overline { 6 } + 1 , \overline { 1 } - 1,5 \times 1 , \overline { \overline { 6 } } ) \times ( 1,25 + 1 , \overline { 6 } \)