Hilbert symbolLet K be any local field. For any two nonzero elements a,b∈K×, we define:(a,b):={+1 if z2=ax2+by2 has a nonzero solution (x,y,z)≠(0,0,0) in K3,-1 otherwise.The number (a,b) is called the Hilbert symbol of a and b in K.