November 16, 2025
Cancel culture meets calculus
Decoding Leibniz Notation (2024)
Math nerds brawl over df/dx—rules vs vibes
TLDR: The article explains that df/dx is a formal symbol for change, not a fraction you can cancel. Comments exploded into purists vs pragmatists: some demand strict rules, others brag they “do algebra” with it because it works, arguing over how calculus should actually be taught.
A calm explainer on Leibniz notation—aka the famous “df/dx” symbol for change—hit the timeline and instantly sparked a nerdy street fight. The post says df/dx isn’t a real fraction you can cancel; it’s a symbol that stands for the derivative, with history’s “tiny changes” idea only a helpful story. Cue the split: purists cheered the “no, you can’t cancel the d’s” mantra, while the pragmatists rolled up with “we do it anyway because it works.”
Top commenter tptacek poked the bear: people literally do algebra with df/dx during substitution in calculus class, and everyone’s guilty. Another voice, sixo, linked Putting Differentials Back into Calculus, basically saying: stop pretending; teach the moves that actually get results. The drama peaked around the second derivative’s messy d²f/dx² notation—should it be (dx)²? Is any of this “real” algebra? The thread turned into a meme factory: “Cancel the d’s? Only if you want your grade canceled,” “df/dx is vibes-first math,” and “engineers don’t care, it gets the job done.”
Verdict from the crowd: the post is a clean tour through the chaos, but the community can’t resist the eternal fight—strict rules vs useful hacks—and df/dx is the hill they’ll die on.
Key Points
- •Leibniz notation historically treated derivatives as ratios of infinitesimal changes df and dx.
- •In modern mathematics, df/dx is a single symbol denoting the derivative function f′, not a literal quotient.
- •The derivative in Leibniz notation denotes a function; evaluation at a point corresponds to f′(a).
- •Second derivatives are written d²f/dx²=f′′ by symbolic convenience, not by true algebraic squaring.
- •Algebra-like manipulations in Leibniz notation (e.g., dx² vs. (dx)², d²) are conventional shortcuts, not formal algebra.