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Showing 1–30 of 360 reference entries

Mathematics & logicExamples and counterexamples

Learn what a claim covers, explain why it works, and recognise an allowed case that shows it needs changing.

Method
Mathematics & logicCounting and zero

Count each object once, explain the final count, and distinguish quantity, position and identifying labels. Make zero’s role explicit.

Definition
Mathematics & logicNumber lines and order

Use number-line positions to compare whole numbers. Read the scale, recognise equality, and distinguish numerical distance from drawing size.

Definition
Mathematics & logicAddition and subtraction

Combine separate counts, remove a part, and find differences or missing parts. Connect objects, equations and number-line moves, then use tens and ones to regroup without changing value.

Definition
Mathematics & logicMultiplication and division

Count equal groups, distinguish sharing from making groups, and check with multiplication. Split calculations into parts; interpret zero and remainders in context.

Definition
Mathematics & logicFractions

Choose a whole, count equal fractional units, and connect sharing with division. Place fractions on the number line, including values beyond one, and explain what their numerator and denominator mean.

Definition
Mathematics & logic · Physics · MeasurementRatios and rates

Distinguish part-to-part ratios, fractions of a whole and rates with units. Scale quantities together, compare unit rates, and explain when a relationship is proportional. Check zero cases, starting amounts and whether a result fits its context.

Definition
Mathematics & logic · Physics · MeasurementQuantities and units

Describe a quantity as a numerical value with a unit, and distinguish its physical kind from its dimension. Build length, area, volume and rate units, check meaningful combinations, and separate exact unit relations from measurement uncertainty.

Definition
Mathematics & logic · Physics · MeasurementUnit conversions

Convert quantities with exact unit ratios, track cancellation through compound units, and apply the correct powers to area and volume. Distinguish temperature readings from differences, check dimensions and context, and retain measurement uncertainty when reporting.

Method
Mathematics & logic · Physics · MeasurementEstimation and uncertainty

Distinguish exact model values, rounded approximations and estimates from measurements. Declare the rounding rule, preserve information through calculations and unit changes, and interpret resolution, precision, accuracy and the stated uncertainty type without turning a report’s digits into guaranteed bounds.

Definition
Mathematics & logicVariables and expressions

Use symbols to name numbers or quantities, describe their allowed values, and evaluate expressions by replacing every occurrence consistently. Preserve grouping, signs, fractions and units, and distinguish a calculated value from solving an equation or proving two rules equivalent.

Definition
Mathematics & logicEquality and equations

Read equality as a relationship, find the permitted values that make an equation true, and justify one-step solutions by reversible operations on both sides. Work exactly with negative numbers and fractions, recognize all-solution and no-solution cases, and check the original equation, units and context.

Definition
Mathematics & logic · PhysicsCoordinates and tables

Locate a point from an ordered pair, read named axes and their scales, and connect the same values in words, tables and plots. Keep signs, fractions and units exact, distinguish an axis point from a quadrant point, and separate selected observations from a stated rule and its domain before drawing connections.

Definition
Mathematics & logic · PhysicsSlope and straight lines

Read a straight line as a stated relationship, calculate its slope from consistent signed coordinate changes, and interpret its intersections with the axes. Keep horizontal, vertical and coincident-point cases distinct, attach units and domain conditions to context models, and use numerical scales rather than appearance alone to judge a line’s change.

Definition
Mathematics & logic · Physics · MeasurementReading graphs

Read a graph’s quantities, units, ticks and context before judging its visual impression. Calculate differences, reference-based percentages and interval rates from the represented values; distinguish legitimate zoom from distorted spacing; and keep samples, interpolation, missing information, uncertainty and causal explanations separate.

Method
Mathematics & logic · PhysicsApproximations

Build a useful estimate, compare a correction with a stated reference scale, and check what is lost when you leave out a term.

Approximation
Mathematics & logic · PhysicsSymmetry and invariance

Specify a transformation, identify what stays unchanged, and distinguish symmetry of an object from invariance of a physical model.

Mathematical statement
Mathematics & logic · PhysicsVectors

Describe displacement with fixed-axis components, combine compatible vectors, and use small exact examples to introduce span, independence, basis and real vector spaces.

Definition
Mathematics & logic · InformationClassical propositions and connectives

Classical logic combines truth-valued propositions using defined connectives.

Definition
Mathematics & logicAxioms, deduction and mathematical proof

A mathematical proof derives a conclusion within stated assumptions and rules.

Method
Mathematics & logic · InformationSets, membership and basic operations

A set specifies membership without counting duplicate listings.

Definition
Mathematics & logic · InformationFunctions, domain and codomain

A function assigns exactly one output to each input in its domain.

Definition
Mathematics & logic · InformationMathematical induction

A base case and general successor step establish a predicate on all nonnegative integers.

Method
Mathematics & logic · MeasurementEuclidean right triangles and the Pythagorean theorem

In a Euclidean right triangle, squared leg lengths sum to the squared hypotenuse length.

Mathematical statement
Mathematics & logic · PhysicsSine, cosine and the unit circle

Sine and cosine are unit-circle coordinates whose squared values sum to one.

Mathematical statement
Mathematics & logic · InformationComplex numbers

A complex number has real coordinates a and b and an imaginary unit satisfying i²=−1.

Definition
Mathematics & logic · Information · PhysicsLinear maps and matrix representation

A linear map preserves linear combinations and has a matrix once bases are chosen.

Definition
Mathematics & logicLimit of a real function

A finite limit controls output error through sufficiently small input distance.

Definition
Mathematics & logic · PhysicsDerivative at a point

A derivative is a finite limit of local difference quotients.

Definition
Mathematics & logic · PhysicsDefinite integral and signed accumulation

A definite integral is the limiting signed accumulation of small contributions.

Definition
DefinitionSource checked

Derivative at a point

Mathematics & logicPhysics

A derivative is a finite limit of local difference quotients.

Key knowledge

For a real function defined on an open interval around a, its derivative at a is the limit of [f(a+h)−f(a)]/h as h approaches zero, if that finite limit exists.

Values and equations

f′(a) = limₕ→₀ [f(a+h) − f(a)]/h

f
Real-valued function near a
a
Point of differentiation
h
Nonzero input increment tending to zero
f′(a)
Derivative when the finite limit exists

Conditions and scope

  • The quotient uses h ≠ 0; both sides must approach the same finite value.
  • If f and its input are measured quantities, the derivative has output units per input unit.
Sources · 3

References

Sources retain their recorded scope. A source link alone does not establish verification of every statement.

  1. Calculus Volume 1, 3.1: Defining the derivativeOpenStaxTextbook chapteropenstax.orgRead source
  2. SI Brochure, ninth edition, version 4.01 (2026)Bureau International des Poids et MesuresReference guide · PDFbipm.orgRead source
  3. Cálculo I · Agenda 09: DerivadasJean Cerqueira Berni, Universidade de São PauloTeaching resource · PDFime.usp.brRead source

Evidence and review

Difference-quotient definition and rate interpretation.

2026-10-10 · Checked limit existence and local-domain conditions.

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

Two-sided difference-quotient derivative at an interior point.

The source also discusses infinite tangent slopes; the repository restricts its derivative to a finite limit.

Entry detailsPermanent link to this entry ↗
Record identity
math-derivatives
Revision
core.1
Structured reference record
Essential core · first collection