theo gt: p + e + n = 34
mà p = e
=> 2p + n = 34
=> n = 34 - 2p (1)
ta có: \(p\le n\le1,5p\) (2)
(1)(2) => \(p\le34-2p\le1,5p\)
\(\Rightarrow\left\{{}\begin{matrix}34-2p\ge p\\34-2p\le1,5p\end{matrix}\right.\)\(\Rightarrow\left\{{}\begin{matrix}p\le11,3\\p\ge9,7\end{matrix}\right.\)
\(\Rightarrow9,7\le p\le11,3\)
=> p = 11
M là Natri ( Na )