Thread: Equation

I need to find the integer solutions to this equation.

Any Idea?
Thanks
everk

xy = x+y or x+y = -xy
the only solution is when x and y = 2 or x and y = -2

suppose y>x
then we can say y=kx+r k is an integer r<x



the left side is a multiple of x so the right should be so should x divides r but x>r then r=0

so y = kx

divde both sides by x



but x is an integer so k should equal 1

and

other case x+y = -xy same

so xy both 2 or both -2

Hi Amer,

Apart from x=y=2 and x=y=-2, wouldn't x=y=0 count as well?