Question

am nevoie de niste ajutor la aceasta problema de clasa a 10a

Answer 1

$\it x,\ y\in\mathbb{N},\ \sqrt{x^2+2y+1}\in\mathbb{Q} \Rightarrow x^2+2y+1=k^2$

$\it x^2+2y+1\geq(x+1)^2\Rightarrow x^2+2y+1\geq x^2+2x+1 \Rightarrow y\geq x \Rightarrow\\ \\ \Rightarrow y(y+1)\geq x(x+1)$