I was given the following multi-variable function $f(x,y)=x+ (xy)^\frac{1}3$. My question is in regards to the usage of dummy variables, and direct substitution in this case.
I have to evaluate the following two:
$f(t,t^2)$
$f(x,x^2)$
My thoughts, and work is that I get the same output $2t$, and $2x$. I am currently new to multi-variable functions. So dummy variables currently apply here, as they do in singular variable mathematics? Is there anything that I should be on the look out for in regards to substitution?