8 26

4

()xy x + y = 8 2x + 4y = 26

9-- algebra

1999 x + 2000 y = 5999 2000 x + 1999 y = 5998

(x , y) x = 1 , y = 2

17 587

20 x

Diophantus

1=2a>0b>0a=b aa2=ab b2 a2 b2 =ab b2 (a + b)(a b ) = b(a b) (a b )a+b = b ba2b=b b2=1

an + bn = cn , n > 2 () 1993

ax2bxc0x1x2 x1x2 -b/a x1 x2c/a 1596-1650abcxyz