Question

[nguyễn châu anh]

TÌM X;Y

X+Y=XY

Answer 1

[shitbo]

x+y=xy

<=>xy-x-y=0

<=>x(y-1)-y+1=1

<=>x(y-1)-(y-1)=1

<=> (x-1)(y-1)=1=-1.(-1)=1.1

+)(x-1)(y-1)=1.1=>x=y=2

+)(x-1)(y-1)=(-1)(-1)=>x=y=0

Vậy....