Answer:
The expression for the magnitude of the accelerations is [tex]a=\frac{g(M-m)}{M+m}[/tex]
Explanation:
According the Newton´s second law:
[tex]Mg - T=Ma,for-mass-M\\T-mg=ma,for-mass-m[/tex]
Clearing T for second equation:
T = ma + mg
Replacing in the first equation:
Mg - ma - mg = Ma
Ma + ma = Mg - mg
a(M + m) = g(M - m)
[tex]a=\frac{g(M-m)}{M+m}[/tex]