Cannot perform the operation: {positive constant} ./ {real affine} how to solve xlog2(1+b/x)

[Mark_L_Stone]

You can find many relevant posts by searching on this forum for
rel_entr . If you study the reformulations and their derivations, yol should be able to improve your ability to figure things out yourself.

Here is one of several which should help you

X*log((ay+x)/(cy+x)) a>c

Assume \begin{array}{l} A = ay + x,\\ B = cy + x,\\ \therefore x\log \left( {\frac{{ay + x}}{{cy + x}}} \right) = \left( {\frac{{A - \frac{a}{c}B}}{{1 - \frac{a}{c}}}} \right)\log \left( {\frac{A}{B}} \right) \end{array} then you have terms like B\log \left( {\frac{A}{B}} \right) and A\log \left( {\frac{A}{B}} \right), those two can be expressed by -rel_entr(B,A) and rel_entr(A,B) respectively, then replace A and B back with the equations above. It might work.