2x+1:y
2y+1:x
y=1 (1) .moi x €N
3:x => x =1,3 =>(x,y)
=(1,1); (3,1) :(1,3) x,y≠1 2x+1=ky 2y+1
=tx 2(x-y)=(k-t)(x-y) (x-y)(2-k+t)
=0 x=y=>x=y=1 x,y≠1 t=k-2 2x+1
=ky 2x+1
=kx -2y kx=(2-k)y => x=
=2-k y=
k x>0=> k<2 y>0=>k>0 k=1 => x=y=1 kl (x,y)=(1,3),(1,1);(3,1)
5 sao nha