Definite integral and signed accumulation
A definite integral is the limiting signed accumulation of small contributions.
Key knowledge
For a continuous real function on [a,b], the definite integral is the limit of sums f(xᵢ*)Δx over successively finer equal subdivisions. It measures signed accumulation; negative contributions subtract rather than become positive area.
Values and equations
∫ₐᵇ f(x) dx = limₙ→∞ Σᵢ₌₁ⁿ f(xᵢ*)Δx
- f
- Continuous real-valued function on [a,b]
- a, b
- Finite integration bounds with a < b
- n
- Number of equal subintervals
- xᵢ*
- Sample point in subinterval i
- Δx
- Subinterval width (b−a)/n
Conditions and scope
- Here a < b and f is continuous, a sufficient integrability condition.
- Choose xᵢ* within each subinterval and Δx=(b−a)/n.
- This entry does not cover improper integrals or every integrable discontinuous function.
Sources · 3
References
Sources retain their recorded scope. A source link alone does not establish verification of every statement.
Evidence and review
Continuous-case Riemann sum and signed area.
2026-10-10 · Checked subdivision and sign conventions; continuity stated as sufficient, not necessary.
Foundational review
2026-10-10 · Fresh primary-source inspection of the complete compact record, including every statement, equation, quantity and material condition, followed by independent AI editorial review. This check does not certify all linked lessons or every passage of every cited publication.
Sources from other places
Scope or convention differs
Sampled subdivisions approach a Riemann integral in the positive-area construction.
The inspected construction is narrower than the repository signed continuous-function statement.
Universidade de São Paulo, Instituto de Matemática e Estatística
- Cálculo I · Agenda 13: Integral de Riemann BrazilPortuguese
§2.1, pp.6–8
- Cálculo I · Agenda 13: Integral de Riemann
Entry details
Permanent link to this entry ↗- Record identity
- math-definite-integrals
- Revision
- core.1
- Structured reference record
- Essential core · first collection