Absolute convergence
Also: absolutely convergent
Absolute convergence guarantees ordinary convergence.
Mathematics glossary
212 terms and notations, organized for quick lookup now and a much larger library later.
Also: absolutely convergent
Absolute convergence guarantees ordinary convergence.
Also: modulus bars · magnitude
Absolute-value bars can also denote magnitude. Their meaning is different from parentheses and from a determinant in later courses.
Also: modulus function
It equals x for nonnegative inputs and -x for negative inputs.
Also: alternating series test
The alternating-series test requires decreasing nonnegative magnitudes tending to zero.
Also: angle notation
The middle letter names the vertex when three points identify an angle.
Also: primitive function
All antiderivatives on an interval differ by an additive constant.
Also: approximation sign · about equal
Use approximate equality after rounding, measurement, or numerical estimation; keep the equals sign for exact identities.
Also: curve length
The square-root factor accounts for simultaneous horizontal and vertical change.
Also: area between graphs
Find intersections and confirm which curve is above on each interval before integrating.
Also: area beneath graph
A plain definite integral gives signed area; absolute value or interval splitting is needed for total geometric area across sign changes.
Also: associativity
Subtraction and division are not associative unless rewritten using inverses.
Also: vertical asymptote · horizontal asymptote
Graphs may approach an asymptote without crossing restrictions implied by the function's domain.
Also: mean value of function
It is the constant height producing the same signed area over the interval.
Also: two-term polynomial
Many factoring patterns, including difference of squares, apply to special binomials.
Also: curly braces
Visible braces usually enclose a set. In LaTeX source, braces also group material without necessarily printing.
Also: chain differentiation
Differentiate the outer function at the unchanged inner expression, then multiply by the inner derivative.
Also: included endpoints
A closed finite interval contains its endpoints and every real number between them.
Also: multiplier
In 7x, the coefficient of x is 7. A missing visible coefficient is often 1 or -1.
Also: commutativity
Subtraction, division, and function composition are generally not commutative.
Also: direct comparison
An upper bound by a convergent positive series proves convergence; a lower bound by a divergent one proves divergence.
Also: complete the square
The method reveals vertex form and provides a general route to the quadratic formula.
Also: concave up · concave down
The second derivative gives a common concavity test where it exists.
Also: conditionally convergent
Conditionally convergent series are sensitive to rearrangement in ways absolutely convergent series are not.
Also: fixed value
A constant does not change within the stated context, even though another problem may assign it a different value.
Also: plus C · integration constant
Better Grades reserves uppercase C for this convention and omits it from definite-integral values.
Also: continuous function
Continuity joins existence of f(a), existence of the nearby limit, and equality between them.
Also: convergent
For a series, convergence means its partial sums approach a finite number.
Also: Cartesian plane
The x-axis is horizontal, the y-axis is vertical, and their intersection is the origin.
Also: critical point
Critical numbers are candidates for extrema, not automatic maxima or minima.
Also: bounded integral
A definite integral is a number when the bounds and function are fixed; it is not an antiderivative family.
Also: degree of polynomial
Degree describes leading growth and helps predict the maximum number of roots.
Also: degrees
A full turn is 360 degrees. Calculus formulas normally use radians unless degrees are explicitly stated.
Also: change symbol
Uppercase delta commonly means a change between two values. Lowercase delta often names a small positive tolerance.
Also: bottom of fraction
The denominator names the divisor and imposes a nonzero restriction.
Also: output variable
In y=f(x), y is dependent because the rule determines it from x.
Also: differentiate · differentiation · instantaneous rate
A derivative is the limit of average rates over shrinking intervals. It is also the slope of the tangent line when that geometric interpretation applies.
Also: instantaneous slope
This number is the instantaneous rate and tangent slope at x=a, when the derivative exists.
Also: d/dx · dy/dx · f prime · dot f
d/dx is an operator; dy/dx is the derivative of y with respect to x; f'(x) names the derivative of f; and a dot conventionally means a time derivative.
Also: d over dx · d/dx
The operator d/dx acts on the expression that follows. By itself it is an instruction, not yet a derivative value.
Also: square difference
Both terms must be squares and the operation must be subtraction over the real numbers.
Also: derivative quotient
The quotient is formed for nonzero h; the derivative comes from its limit as h approaches zero.
Also: dx · dy
In an integral, dx states the variable of accumulation. In differential notation, dy=f'(x)dx records a linear change relationship.
Also: taking a derivative
Differentiation applies limit definitions or valid derivative rules while preserving the named independent variable.
Also: direct proportion
The constant k is both y/x and the line's slope.
Also: break in graph
A discontinuity may be removable, a jump, infinite, or oscillatory depending on the failure.
Also: b squared minus 4ac
A positive discriminant gives two real roots, zero gives one repeated real root, and a negative value gives nonreal conjugates.
Also: distribute
Distribution preserves equivalence and works in reverse when factoring.
Also: divergent
Divergence can mean unbounded growth, oscillation, or another failure of a required limit.
Also: obelus
Better Grades usually uses a fraction bar in algebra because it makes grouping explicit.
Also: input set
A formula's domain excludes inputs that make an operation undefined, and a model may impose additional contextual restrictions.
Also: Newton notation · y dot
A dot over a quantity conventionally means one time derivative; two dots mean the second time derivative.
Also: member
Membership uses the element-of symbol; it is different from being a subset.
Also: linear combination
Scaling and adding or subtracting aligned equations can reduce a system to one variable.
Also: dots
Dots omit intermediate terms only when the continuation rule is clear from context.
Also: null set
The empty set is a set, not the number zero and not a missing answer.
Also: equality sign
The equals sign joins expressions that are equal. It should not be used merely to mean “the next line.”
Also: equality
Solving an equation means finding the permitted values that make its equality true.
Also: equivalent forms
Equivalence may depend on domain restrictions; canceling a factor does not restore an excluded input.
Also: natural base · Euler number
Euler's number is the base whose exponential function is its own derivative.
Also: bounds bar
The evaluation bar means F(b) minus F(a). It is not an absolute-value bar in this context.
Also: power notation · superscript
The superscript is the exponent. Its meaning extends from positive integers to zero, negative, rational, and real exponents under appropriate domain rules.
Also: exponential model
With positive base b not equal to one, the function models repeated multiplicative change.
Also: algebraic expression
An expression can be evaluated or simplified, but it is not solved until it appears in a statement such as an equation.
Also: extraneous root
Squaring, clearing denominators, and some other nonreversible steps can introduce extraneous candidates.
Also: multiplicative factor
Factors may cancel only across a product and only when their nonzero restrictions are retained.
Also: factorial sign
For a nonnegative integer n, n factorial is the product from n down to 1, with 0! defined as 1.
Also: factorization
Factoring exposes zeros, common structure, and legal cancellations.
Also: vinculum · division bar
A fraction bar groups the entire numerator and denominator and means division, provided the denominator is nonzero.
Also: mapping
Different inputs may share an output, but one allowed input cannot have two outputs in a function.
Also: circle operator · composite function
Composition is evaluated from the inside outward and is generally not commutative.
Also: f of x
The parentheses identify the input to f; f(x) does not mean f multiplied by x.
Also: FTC
When F'=f under the theorem's hypotheses, endpoint evaluation computes the definite integral.
Also: geometric sum
It converges to a/(1-r) when |r|<1 and diverges otherwise.
Also: at least · geq
The symbol combines an order comparison with equality, so the endpoint is included.
Also: greater than
The open side faces the larger value and the point faces the smaller value.
Also: GCF · greatest common divisor
Factoring out the GCF is the first check before applying more specialized patterns.
Also: decay factor
Growth uses b greater than one; decay uses a factor between zero and one.
Also: algebraic identity
An identity differs from a conditional equation, which is true only for particular solutions.
Also: iff · biconditional
A biconditional records two implications and therefore an equivalence of conditions.
Also: i
The imaginary unit extends the real numbers to the complex numbers. It is not an index when used in this role.
Also: implicit derivative
Every y-dependent term receives a dy/dx factor because y is treated as a function of x.
Also: right arrow · therefore implies
An implication runs in one direction. Its reverse requires separate justification.
Also: infinite integral
It is defined by a limit and converges only when that limit is finite.
Also: antiderivative integral
The constant C is required because differentiation removes additive constants.
Also: input variable
In y=f(x), x is the independent variable unless the context defines another dependency.
Also: 0 over 0 · infinity over infinity
Different functions can share an indeterminate form and have different limits, so further analysis is required.
Also: subscript index
Indices are conventionally lowercase integers such as n, k, i, or j, with their starting value stated.
Also: order statement
An inequality often has an interval or union of intervals as its solution set.
Also: unbounded limit
The infinity symbol records unbounded behavior rather than a real-valued limit.
Also: infinity
Infinity indicates that a quantity grows without bound. Ordinary arithmetic rules for finite numbers do not automatically apply to it.
Also: point of inflection
A zero or undefined second derivative is only a candidate; the concavity must actually switch.
Also: independent value
The input belongs to the domain and is commonly written inside function parentheses.
Also: Z · integer set
The integers contain no fractional part and extend without bound in both directions.
Also: integration sign
The elongated S recalls summation. Bounds make the integral definite; no bounds usually asks for a family of antiderivatives.
Also: integral convergence test
Under the test's continuity, positivity, and decrease conditions, the series and integral converge or diverge together.
Also: inside integral
The integrand includes its algebraic structure but not the integral sign, bounds, or differential.
Also: parts formula · IBP
Choose u so differentiation simplifies it and dv so it can be integrated cleanly.
Also: cap symbol
Intersection corresponds to “and” between membership conditions.
Also: interval notation
Parentheses exclude endpoints and brackets include them. Infinity always uses a parenthesis.
Also: functional inverse
An inverse function is not the reciprocal 1/f(x). Its domain and range exchange roles with the original.
Also: undo operation
Equation solving uses inverse operations while applying the same legal move to both sides.
Also: inverse proportion
As one nonzero quantity grows, the other shrinks so xy=k.
Also: leading number
The leading coefficient and degree control a polynomial's end behavior.
Also: at most · leq
The symbol combines an order comparison with equality, so the endpoint is included.
Also: less than
The point faces the smaller value and the open side faces the larger value.
Also: similar terms
Only coefficients of like terms combine; unlike powers remain separate.
Also: limiting value
A limit describes nearby behavior and may exist even when the function is undefined or has another value at the target.
Also: limit comparison
A finite positive c means the two positive-term series share convergence behavior.
Also: straight line · ell
A lowercase script ell may name a geometric line; this prevents confusion with an ordinary scalar variable.
Also: first-degree equation
A one-variable linear equation has one, no, or infinitely many solutions after simplification.
Also: line function
Its graph is a nonvertical line, with slope m and vertical intercept b.
Also: linear approximation
Linearization is most accurate near a and needs an error discussion when used farther away.
Also: relative maximum
A local maximum is defined relative to a neighborhood and need not be the largest value on the whole domain.
Also: relative minimum
A local minimum is defined relative to a neighborhood and need not be the smallest value on the whole domain.
Also: log
A logarithm is defined for positive arguments and is the inverse of an exponential function with the same base.
Also: Maclaurin expansion
Maclaurin notation simplifies common expansions around the origin.
Also: mapsto
The maps-to arrow separates an input pattern from the output assigned by a rule.
Also: model
A model includes assumptions, units, and a useful domain; matching data alone does not make it universally valid.
Also: MVT
If f is continuous on [a,b] and differentiable on (a,b), at least one c in the open interval satisfies the equation.
Also: one-term polynomial
A monomial coefficient may be any real number and its variable exponents are nonnegative integers.
Also: times sign
The cross means multiplication in elementary contexts, but later it can denote a vector cross product or Cartesian product.
Also: center dot
The centered dot is useful between numbers, units, or complicated factors where adjacency could be ambiguous.
Also: del operator · gradient symbol
Nabla is read “del.” In multivariable calculus it combines partial-derivative directions.
Also: ln
The natural logarithm is defined for positive real x and appears naturally in calculus and continuous growth.
Also: N · counting numbers
Conventions differ about whether zero is natural, so Better Grades states the starting index when it matters.
Also: not symbol · slashed relation
The not command places a slash through a relation. Read the resulting combined symbol as one negated statement, not as subtraction.
Also: negative power
A negative exponent does not make the base negative; it records reciprocal multiplication.
Also: Newton-Raphson method
Success depends on a sensible starting value and nonzero derivatives; convergence is not automatic.
Also: not an element of
The slashed membership symbol excludes the left-hand object from the set on the right.
Also: not equal · neq
The not-equal sign excludes equality between the quantities on its two sides.
Also: top of fraction
The numerator is the quantity being divided. It may contain several grouped terms.
Also: left-hand limit · right-hand limit
One-sided limits describe a single branch near a boundary or jump.
Also: excluded endpoints
Every point between a and b is included, while a and b are not.
Also: coordinate pair
In the coordinate plane, the first coordinate is horizontal and the second is vertical.
Also: dependent value
Outputs form the range and may be described by a dependent variable such as y.
Also: p series test
The p-series converges exactly when p is greater than one.
Also: quadratic graph
Its opening direction and width depend on a, while its vertex and axis come from h and k.
Also: parallel lines
Distinct nonvertical parallel lines have equal slopes and different intercepts.
Also: model parameter
Parameters such as m and b choose one member of a model family; variables then range within that chosen model.
Also: round brackets
Parentheses control operation order and enclose function arguments. They also mark excluded interval endpoints.
Also: partial fraction decomposition
Factor the denominator, choose a template, solve coefficients, then integrate or simplify the pieces.
Also: nth partial sum
A series converges when the sequence of partial sums S_n converges.
Also: partial d
The rounded partial symbol distinguishes a partial derivative from an ordinary single-variable derivative.
Also: percentage
Convert a percent to a decimal by dividing by 100 before using it as a multiplier.
Also: square trinomial
The first and last terms are squares and the middle term is twice their signed product.
Also: right angle
For nonvertical lines in the coordinate plane, perpendicular slopes are negative reciprocals.
Also: circle constant
Pi is an exact irrational constant used throughout geometry, trigonometry, and calculus.
Also: piecewise definition
Each input must be evaluated with the rule whose condition contains it.
Also: plus minus · pm
The plus-or-minus sign abbreviates two statements: one using plus and one using minus.
Also: point slope
The form is especially useful when the y-intercept is not known.
Also: polynomial expression
Polynomial degree is the largest exponent with a nonzero coefficient.
Also: series in powers
A power series converges inside a radius, diverges outside it, and needs endpoint checks.
Also: f prime · apostrophe notation
One prime means the first derivative; additional primes indicate higher derivatives. The independent variable is inferred from the function input.
Also: derivative of product
Differentiating each factor and multiplying the results is not the product rule.
Also: product notation · capital pi
Capital pi notation is the multiplicative counterpart of summation notation.
Also: equal ratios
A proportion can be solved by valid equation operations; cross multiplication is shorthand when denominators are nonzero.
Also: second-degree
A quadratic graph is a parabola and may have zero, one, or two real zeros.
Also: quadratic equation formula
The formula follows from completing the square and works even when a quadratic does not factor nicely.
Also: derivative of quotient
The rule applies where g is nonzero and keeps the numerator order significant.
Also: root expression
Simplifying a radical removes perfect-power factors while respecting real-domain restrictions.
Also: root sign · square root symbol
The small index names the root. An even real root requires a nonnegative radicand.
Also: convergence radius
Endpoints at distance R must be tested separately.
Also: output set
Range depends on both the rule and its domain. It is not automatically every real number.
Also: rate
Average rate uses finite changes; instantaneous rate is described by a derivative.
Also: comparison
A ratio compares quantities in a stated order and should preserve meaningful units.
Also: d'Alembert ratio test
The series converges absolutely if L<1, diverges if L>1, and the test is inconclusive if L=1.
Also: fraction equation
Record denominator restrictions before clearing fractions, then check candidates in the original equation.
Also: fractional exponent
Real-domain restrictions depend on the root index and the base.
Also: algebraic fraction
Zeros of the original denominator are excluded even if a common factor later cancels.
Also: R · reals
The real numbers include rational and irrational numbers but not nonreal complex values.
Also: multiplicative inverse
A quantity times its reciprocal equals one. Zero has no reciprocal.
Also: rates problem
Differentiate the constraint with respect to time before inserting the values at the requested instant.
Also: input-output relation
A relation becomes a function only when each input is paired with no more than one output.
Also: hole
Defining or redefining f(a)=L repairs continuity without changing nearby values.
Also: Rolle theorem
Rolle's theorem is the equal-endpoint special case of the mean value theorem.
Also: Cauchy root test
The conclusion rule matches the ratio test and is especially useful when the nth term is raised to the nth power.
Also: secant slope
Its slope is the average rate of change across the interval from a to b.
Also: number sequence
Order and repetition matter in a sequence. A formula or recurrence may define its terms.
Also: infinite series
An infinite series is defined through the limit of its finite partial sums.
Also: collection
A set is determined by membership, not by the order in which elements are listed.
Also: element of · in symbol
The membership symbol relates an element on the left to a set on the right.
Also: gradient · rise over run
Slope records a constant rate of change for a line. A vertical line has undefined slope.
Also: y equals mx plus b
m is the slope and (0,b) is the y-intercept.
Also: root · answer
A candidate becomes a solution only after it satisfies the original equation, inequality, or system and its domain restrictions.
Also: answer set
A solution set may be finite, an interval, a union, empty, or an entire allowed domain.
Also: brackets
In interval notation, square brackets mean the endpoint is included. In formulas they can provide a second grouping level.
Also: sandwich theorem
When g and h approach the same value, the trapped function f must approach it too.
Also: standard form
By site convention, uppercase A, B, and C are reserved here for the traditional standard-form coefficients.
Also: index notation
A subscript distinguishes members of a sequence, coordinates, parameters, or related quantities.
Also: contained in
The subset-or-equal symbol allows the two sets to be identical. A strict subset convention should be stated when ambiguity matters.
Also: solve by substitution
Substitution reduces a system when one variable is already isolated or easy to isolate.
Also: sigma · sum sign
Sigma notation states the index, starting value, ending value, and expression to add.
Also: surface of revolution
The integrand combines circumference with the curve's arc-length element.
Also: simultaneous equations
A system may have one solution, none, or infinitely many depending on how its constraints intersect.
Also: tangent
When differentiability holds, its slope is the derivative at the point.
Also: error term · Taylor error
A remainder bound turns a finite approximation into a quantitative accuracy statement.
Also: Taylor expansion
The series represents f only where its remainder approaches zero.
Also: algebraic term
Signs belong to their terms. Factors inside one term are multiplied together.
Also: long arrow · becomes arrow
A long transition arrow organizes a calculation or approach. It does not automatically assert the logical implication represented by a double arrow.
Also: three-term polynomial
Quadratic trinomials often factor into two binomials when suitable numbers exist.
Also: ordinary limit
A finite two-sided limit exists exactly when both one-sided limits exist and equal the same value.
Also: substitution rule · change of variable
A useful substitution absorbs an inner expression and its differential factor, with bounds changed for definite integrals.
Also: cup symbol
Union corresponds to an inclusive “or” between membership conditions.
Also: per unit
Unit rates make proportional comparisons and dimensional interpretation easier.
Also: measurement units · dimensions
Units participate in multiplication and division and provide a strong check on formulas and answers.
Also: unknown
A variable represents a quantity. Better Grades uses lowercase italic letters for ordinary scalar variables unless a documented convention requires otherwise.
Also: turning point
In vertex form y=a(x-h)^2+k, the vertex is (h,k) and the axis is x=h.
Also: washer method · shell method
Washers use outer and inner radii; shells use circumference, radius, and height.
Also: work done
When force varies with position, the work integral adds force times small displacement.
Also: horizontal intercept · zero
At an x-intercept the output coordinate is zero, so finding intercepts often means solving f(x)=0.
Also: vertical intercept
At a y-intercept the input coordinate is zero, provided zero belongs to the domain.
Also: zero factor property
The property applies after one side of an equation has been set equal to zero and the other side is factored.