PLease help with this i cannot find anything like this in my textbook

s  =  [ u^2 + v^2]  / [ 2uv]  =  [ u^2 + v^2] [ 2uv]^(-1)

ds/ du     [ Here...we treat  v as a constant]....so  we have [  using the product and chain rules ]

[ 2u + v^2] [ 2uv]^(-1)   - (2v)  [ u^2 + v^2] [ 2uv]^(-2)  

Similarly

ds /dv  [ we treat u as a constant ]

[ u^2 + 2v] [ 2uv]^(-1) - (2u) [ u^2 + v^2] [ 2uv]^(-2)

so is that weird symbol a d?

 a derivative ?