Question

Ajutati-ma va rog, faceti oricare exercitiu puteti de aici ( de dorit toate ). Dau 25 puncte.

Answer 1

6)

$\it a=(x+3)^2 - 2x - (2+x)^2=x^2+6x+9-2x-4-4x-x^2 =9-4=5\in\mathbb{N}$