[问答题]
Show that when a nuclzjkk6g0c6f7 m eusmwhgc5f k ju+)jwl )g /(xss;4 decays by $\beta^+$ decay, the total energy released is equal to
$Q = (M_P - M_D - 2m_e)c^2$
where $M_P$ and $M_D$ are the masses of the parent and daughter atoms (neutral), and $m_e$ is the mass of an electron or positron.