Em làm được bài nào trong 3 bài này chưa em?
Bài 1:
\(\left\{{}\begin{matrix}P+E+N=28\\P=E\\N=10\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}2P+N=28\\N=10\end{matrix}\right.\\ \Leftrightarrow\left\{{}\begin{matrix}P=E=Z=\dfrac{28-10}{2}=9\\N=10\end{matrix}\right.\\ Vì:Z=9\Rightarrow X.thuộc.nguyên.tố.Flo\left(Z_F=9\right)\)
Bài 2:
\(\left\{{}\begin{matrix}P+E+N=52\\\left(P+E\right)-N=16\\P=E\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}2P+N=52\\2P-N=16\end{matrix}\right.\\ \Leftrightarrow\left\{{}\begin{matrix}P=E=Z=18\\N=16\end{matrix}\right.\)
Bài 3:
\(\left\{{}\begin{matrix}P+E+Z=52\\P=E\\N-P=1\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}2P+N=52\\N-P=1\end{matrix}\right.\\ \Leftrightarrow\left\{{}\begin{matrix}P=E=Z=17\\N=18\end{matrix}\right.\)
