Hi,

What you have asked us to do is to solve the expression $y = 1.5 x + \log(1+x)$ for $x$ to obtain an expression of the form

\[ x = \mbox{ "some mathematical expression in } y" = f(y).\]

Unfortunately there is no such mathematical expression $f(y)$ that can be written in terms of polynomials, rational functions, trigonometric functions, logarithms or exponents. The function $f(y)$ you want is a perfectly good mathematical function, it just cant be written in terms of the usual mathematical expressions.

Penny