When a problem is expressed like this $F(x,y)$ then you are asked to find $F_x(x,y)$
My understand is that means you need to find the partial derivative of $x$, which means $y$ is held and treated as constant ? Is this correct or does it need to use that funny little partial derivative symbol ?
Thanks,
Your opinion is correct: $F_x$ means the derivative of $F$ with respect to the $x$ variable, and $y$ is kept constant. It is just an alternative notation to $$ \frac{\partial F}{\partial x}, \quad D_xF, \quad \partial_x F, \quad \partial_1 F. $$