Rewrite this in terms of f, f, ∂f/∂x, and x:
∂f(x,y)/∂(%Δx) = ∂f(x,y)/∂(d log(x) )
∂(%Δf(x,y))/∂(%Δx) = ∂logf(x,y)/∂log(x)= ∂f(x,y)/∂x*x/f(x,y).
The Attempt at a Solution
I found that (%Δx) can be written as the differential of log(x):
∂f(x,y)/∂(%Δx) = ∂f(x,y)/∂(d log(x) ).
But the partial of derivative of differential of the variable throws me off. It seems like the valid problems that people may have in real world: how much the level of function changes if you increase 1% of the variable, but I can't find anything on it.