I was preparing some implicit differentiation exercises and decided to give this one:
If find That is fairly straight forward, no? But there is a bit more here than meets the eye, as I quickly found out. I graphed this on Desmos and:
What in the world? Then I pondered for a minute or two and then it hit me:
which leads to families of lines with either slope 1 or slope negative 1 and y intercepts multiples of
Now, just blindly doing the problem we get which leads to: by both the original equation and the circle identity.