Hi Edoardo,
Refer the expand function, and Children function documentation. Refer link for various other Functions to Rearrange Symbolic Expressions.
The Following code shows an example for your use case,
syms a b m y
y = (a^m/b^(m+2));
y = expand(y);
[N,D] = numden(y);
D_Split = children(D);
T1 = N/D_Split(1); % (a/b)^m
T2 = 1/D_Split(2); % (1/b^2)
Kiran Felix Robert
