Leibniz notation Memes

The eternal calculus paradox that haunts undergrads everywhere. First, the professor confidently states that du/dt = (du/dx)(dx/dt), treating du/dx like a perfectly normal fraction. Then when a student dares to ask if du/dx is actually a fraction, suddenly it's "No." Welcome to mathematics, where we use fraction notation for things that aren't fractions, cancel terms that technically can't be canceled, and somehow still get the right answer. Schrödinger's fraction—simultaneously a fraction and not a fraction until a student asks about it.