1. Lattice Points

How many lattice points, whose coordinates are integers, are on circle
(x + 1)^2 + (y - 2)^2 = 2?

I believe the answer is 4?

2. Can you justify your answer? What if the RHS was 5^2?

3. Originally Posted by Ackbeet
Can you justify your answer? What if the RHS was 5^2?
I cannot. I used GeoGebra to graph the circle and it looks like the answer is four. However, I am starting to lean towards zero because the radius is not a real number. Any thoughts?

RHS?

4. You are correct.
Look at the graph.