Question

urgent dau coroana ︎ ︎ ︎ ︎ ︎ ︎ ︎︎ ︎ ︎︎ ︎ ︎ ︎ ︎ ︎ ︎︎ ︎ ︎︎ ︎ ︎ ︎ ︎ ︎ ︎︎ ︎ ︎︎ ︎ ︎ ︎ ︎ ︎ ︎︎ ︎ ︎​

Answer 1

Explicație pas cu pas:

$a = {( - 1)}^{k} \cdot ( - 3) + {( - 1)}^{k + 1}\cdot ( - 5) + {( - 1)}^{k + 2}\cdot 2$

→ k = par

$a = {( - 1)}^{k} \cdot ( - 3) + {( - 1)}^{k + 1}\cdot ( - 5) + {( - 1)}^{k + 2}\cdot 2 = ( - 3) + ( - 1)\cdot ( - 5) + 2 = - 3 + 5 + 2 = 7 - 3 = 4$

→ k = impar

$a = {( - 1)}^{k} \cdot ( - 3) + {( - 1)}^{k + 1}\cdot ( - 5) + {( - 1)}^{k + 2}\cdot 2 = ( - 1) \cdot ( - 3) + ( - 5) + ( - 1)\cdot 2 = 3 - 5 - 2 = 3 - 7 = - 4$

=> 4 | a, oricare ar fi k ∈ N