Question

aflati nr natural din proportia x supra 4=9 supra x​

Answer 1

$\it \dfrac{x}{4}=\dfrac{9}{x} \Rightarrow x\cdot x=4\cdot9 \Rightarrow x^2=36 \Rightarrow \sqrt{x^2}=\sqrt{36} \Rightarrow |x|=6 \Rightarrow x=\pm6$

$\it x\in\mathbb{N} \Rightarrow x=6$