2*x+1+x-1-2*sqrt((2*x+1)(x-1))=a²
3*x-2*sqrt(2*x²-2*x+x-1)=a²
3*x-2*sqrt(2*x²-x-1)=a² => 2*sqrt(2*x²-x-1)=3*x-a²
9*x²-12*x*sqrt(2*x²-x-1)+4*(2*x²-x-1)=a^4
2*sqrt(2*x²-x-1)
9*x²-6*x*(3*x-a²)+4*(2*x²-x-1)=a^4
9*x²-18*x²+6*x*a²+8*x²-4*x-4=a^4
-x²+2*x*(3*a²-2)-4-a^4=0
x = 3*a²-2*(sqrt(a²*(2*a²-3))+1) или x = 3*a²+2*(sqrt(a²*(2*a²-3))+1)