Is Va entirely arbitrary or does it have some particular form? I'm assuming it's a source rather than the desired output from some initial value conditions of the circuit... the problem statement is rather vague.
Hi thanks for your anwers, yes I1 is an inductor,
I1=integral of (Va-V1)/L, but in all this equations where i use the resistor R, i think R is part of I1, but i dont know how write the equation in this case.
The potential at the left side of L1 is not Va since, as you say the resistor R is between it and the reference node. There will be a potential drop across R due to ##I_1##. So the potential across L1 is going to be something like: ##(-I_1 R + V_a - V_1)##.