I'll leave out all the gory details - it took pages and pages along with a couple of false starts. It took me a minute to see the branches when y<0 - it curves back on itself. I had to solve a quartic to get the 4 vertical tangents so I just used the decimal approx. to save space. The 3 and 5 are not exact but they were close enough. I do have the exact values, but as I said, takes up too much space for here. Lots of fun. Thanks - Ian

I'll leave out all the gory details - it took pages and pages along with a couple of false starts. It took me a minute to see the branches when y<0 - it curves back on itself. I had to solve a quartic to get the 4 vertical tangents so I just used the decimal approx. to save space. The 3 and 5 are not exact but they were close enough. I do have the exact values, but as I said, takes up too much space for here. Lots of fun. Thanks - Ian