Question

 

tim tat ca cac cap so nguyen x, y sao cho : xy - 2x + y + 1 = 0

 

Answer 1

xy-2x+y+1=0

=>xy-2x+y=-1

=>x.(y-2)+y=-1

=>x.(y-2)+y-2=-1-2

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

=>y-2,x+1thuộc Ư(-3)={1;-1;3;-3}

y-2	1   -1   3   -3
x+1	3   -3   1   -1
y	3   1   5     -1
x	2  -4   0    -2

vậy x=2;y=3

      x=-4;y=1

     x=0; y=5

     x=-2;y=-1

Answer 2

xy-2x+y+1=0

=>xy-2x+y=-1

=>x.(y-2)+y=-1

=>x.(y-2)+y-2=-1-2

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

=>y-2,x+1thuộc Ư(-3)={1;-1;3;-3}

y-2	1   -1   3   -3
x+1	3   -3   1   -1
y	3   1   5     -1
x	2  -4   0    -2

vậy x=2;y=3

      x=-4;y=1

     x=0; y=5

     x=-2;y=-1