回复：We only check |y^2-P|=2,If there is no solution,the Q has no

Jinjing's method provided one way to look for integral solutions for Pell's equation.  from (x+1)(x-1)=Dy^2 and (x+1) - (x-1) = 2 we have to learn (x+1)-(x-1) = (....-...)*2. That is great!