Question

x²+xy-2=0

tìm số nguyên dương x , y

Answer 1

3x+xy-y-5=0

<=>x(3+y)-(y+3)=2

<=>(y+3)(x-1)=2=1.2=(-1).(-2)

Do x;y là sô nguyên =>

*)y+3=1;x-1=2

<=>y=-2;x=3

*)y+3=2;x-1=1

<=>y=-1;x=2

*)y+3=-2;x-1=-1

<=>y=-5;x=0

*)y+3=-1;x-1=-2

<=>y=-4;x=-1

gợi  ý   nha 

Answer 2

x²+xy-2=0

x²+xy=2

x(x+y)=2

x,x+y thuộc Ư(2)

=>x=y=1

    x=2;y=0