Question

Va rog mult dau coroana!​

Answer 1

$\it a=1+2+3+\ ... \ +20=\dfrac{20\cdot21}{2}=10\cdot21=210\\ \\ \\ b=2+4+6+\ ...\ +50=2(1+2+3+\ ...\ +25)=\not2\cdot\dfrac{25\cdot26}{\not2}=650\\ \\ \\ a\leq x^2\leq b \Rightarrow 210\leq x^2\leq650\ \stackrel{x\in\mathbb{N}}{\Longrightarrow}\ M=\{15,\ 16,\ 17,\ ...\ ,\ 25\}$

Answer 2

Răspuns:

Explicație pas cu pas: