>>74
x-1=(√2+1)/(√2-1)-1
=(√2+1)/(√2-1)-(√2-1)/(√2-1)
=(√2+1-√2+1)/(√2-1)
=2/(√2-1)

y-1=(√2-1)/(√2+1)-1
=(√2-1)/(√2+1)-(√2+1)/(√2+1)
=(√2-1-√2-1)/(√2+1)
=(-2)/(√2+1)
よって
(x-1)(y-1)={2/(√2-1)}{(-2)/(√2+1)}