Proofs
Browse a catalog of interesting and common proofs, from core analysis and linear algebra arguments to standard proof techniques worth knowing well.
Showing 4 proofs in Calculus.
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Proof that the derivative of a constant function is zero
This proof is short, but it matters because it shows the derivative definition already knows that a function with no change has zero slope. Nothing extra has to be added as a rule.
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Proof that for positive integers
This proof shows where the power rule comes from rather than treating it as a black box. The binomial theorem isolates the only term that survives after dividing by and taking the limit.
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Proof of the chain rule
The chain rule says the derivative of is . The proof uses a continuous extension of the difference quotient to handle all cases cleanly.
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Proof that a differentiable function is continuous
This proof shows why differentiability is a stronger condition than continuity. The difference factors into a difference quotient times , and that product is forced to zero.
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