the last question on my precalculus test

Here's the last question on a precalculus test I gave out this week. I asked the students to find the inverse of a rational function. In order to make this more fun, I gave them an involutory function. That is, the inverse function is actually the same as the original, f^-1(x)=f(x) or f(f(x))=x. Some students noticed the answer and told me it was a tricky question. #math #precalculus #blackpenredpen
Read more on involutory functions: https://en.wikipedia.org/wiki/Involut...)

0:00 how I have fun when I teach math classes
0:33 the precalculus way to find the inverse of a function
3:28 finding the involution for rational functions
13:21 a much better way!

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