Solving Variational Equations with FreeFem++

[urric]

Hi, sorry if this isn't the correct forum.
I'm trying freefem++ to solve some some problems with finite elements method, but in the documentation the following form of the variational equation is used:

\displaystyle\int_{T_{h}} (\frac{{\partial u}}{{\partial x}}\frac{{\partial v}}{{\partial x}} + \frac{{\partial u}}{{\partial y}}\frac{{\partial v}}{{\partial y}} )dxdy =\displaystyle\int_{T_{h}} fvdxdy

I've searched for that form, but I wasn't able to find it

Could you tell me about a book or any source where I can study that form of the variational equation?

Thanks

 

[fresh_42]

Looks strange without any imaginary units, time parameters or simply the order in the integral on the LHS.
Some context would be more than helpful.