# Another Math “Joke”

Sum 1 to N writes the following:

A math professor is proving some general theorem, and ends up with a result involving $x$â€™s and $y$â€™s. One student raises his hand and asks, â€œCan you show us a special case of that theorem?â€. In other words, the student wanted a specific application of the theorem. The professor proceeds to erase the $x$â€™s and $y$â€™s and replace them with $x_0$â€™s and $y_0$â€™s. The student replies, â€œAh! That makes more sense.â€

As it is trivially obvious to the most casual observer, the extension of the theorem to $x_1$ and $y_1$ is left as an exercise to the interested reader.

And it will be on the test.