# What does r in an answer mean

After I ran the following I got a valid image but what do the `r`

's
stand for in the solve part? They don't seem to have a value
but I didn't get an error.

```
var('x y')
show(plot3d(x^2 + y^2, (x,-2,2), (y,-2,2)))
```

[image]

```
solve(x^2 + y^2==0,[x,y])
[[x == r1, y == I*r1], [x == r2, y == -I*r2]]
```

For some reason the y answer is sqrt(-1) times r1, etc, but isn't showing up in my query.