How to rewrite an expression Let's say $Z=Y_1+Y_2$. I have this expression: $Y_1!Y_2!$. I want to rewrite the expression and express it by only $Z$. Is that possible?
No, because for example if you take $Y_1=5$, $Y_2=7$ or if you take $Y_1=4$, $Y_2=8$, then both give the same $Z$ but different $Y_1!Y_2!$.
Not possible. Consider $Z=4$ with $Y_1 = 1$ and $Y_2 = 3$, you'll get an answer of $6$. Now try this with $Y_1 = 2$ and $Y_2 = 2$, you'll get an answer of $4$.