A Clue, Holmes!
Sherlock Holmes finds the point-slope equation of a tangent line and concludes it must be the work of a malicious mind: a mathematician.
Transcript
[Watson holds a page: a curve with tangent line at (h,k), y − k = f′(h)(x − h)] "Look, Holmes! A clue! But… what does it mean?" Holmes: "Who can say, Watson? It is written in an inscrutable code, which suggests only a paranoid mind of tremendous malice. I suspect a mathematician."
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Free for classrooms, worksheets, slides and other non-commercial use under CC BY-NC 4.0, with credit to Ben Orlin.
Cartoon by Ben Orlin, Math with Bad Drawings. https://cartoons.mathwithbaddrawings.com/2019-10-08-a-clue-holmes/ (CC BY-NC 4.0)