**In 1768, Lagrange gave the first complete proof of the solvability of **

x^{2} - Dy^{2} = 1 ( complicated)

*I erased a wrong statement - please see my next post*

**OUT OF THE THREE GIVEN EQUATIONS ****WE CAN FULLFIL THE FIRST AND THE LAST e.g. D=2 y=2 =>>x^2=1+8=9 OK**

**D=6 y=2 ==>>x^2=1+24=25 OK**

**but not the second x^2=1+12=13 NOT A SQUARE**

**Rem: puzzle's x is our y ; D=2,3,6**

*Edited on ***January 10, 2010, 1:13 pm**