Glossary

A

Algebraic Manipulation

Criticality: 2

The process of transforming mathematical expressions using algebraic rules, such as factoring, expanding, or rationalizing, to simplify them or make them easier to evaluate.

Example:

Before finding the limit of x24x2\frac{x^2 - 4}{x - 2} as xo2x o 2, you would use algebraic manipulation to factor the numerator and cancel the common term.

C

Composite Function

Criticality: 2

A function formed by applying one function to the results of another function, often written as $f(g(x))$.

Example:

If f(x)=x2f(x) = x^2 and g(x)=sinxg(x) = \sin x, then g(f(x))=sin(x2)g(f(x)) = \sin(x^2) is a composite function.

Conjugate

Criticality: 2

For a binomial expression involving a square root, its conjugate is formed by changing the sign of the second term (e.g., the conjugate of $a - \sqrt{b}$ is $a + \sqrt{b}$).

Example:

To rationalize the denominator of 131\frac{1}{\sqrt{3}-1}, you would multiply by its conjugate, 3+1\sqrt{3}+1, on both the numerator and denominator.

Continuous Function

Criticality: 3

A function whose graph can be drawn without lifting the pen, meaning it has no breaks, jumps, or holes.

Example:

The function f(x)=x2f(x) = x^2 is a continuous function because its graph is a smooth, unbroken parabola.

Continuous Function

Criticality: 3

A function whose graph can be drawn without lifting the pen, meaning it has no breaks, jumps, or holes.

Example:

A polynomial function like f(x)=x2+3x1f(x) = x^2 + 3x - 1 is a continuous function for all real numbers, as its graph is a smooth, unbroken curve.

F

Factorizing

Criticality: 2

The process of breaking down a polynomial or expression into a product of simpler expressions (factors).

Example:

The expression x25x+6x^2 - 5x + 6 can be factorized into (x2)(x3)(x-2)(x-3).

Finite Limit at Infinity

Criticality: 3

The specific numerical value that a function approaches as its input (x) increases or decreases without bound (tends to positive or negative infinity).

Example:

If limxof(x)=7\lim_{x o \infty} f(x) = 7, then 7 is the finite limit at infinity, which directly corresponds to a horizontal asymptote at y=7y=7.

G

Graph

Criticality: 2

A visual representation of a function's behavior, which can be used to estimate limits and identify asymptotic trends.

Example:

Observing the graph of f(x)=1xf(x) = \frac{1}{x} clearly shows its behavior near x=0x=0 and as xx extends towards positive or negative infinity.

H

Horizontal Asymptote

Criticality: 3

A horizontal line that the graph of a function approaches as the input variable increases or decreases without bound, indicating a finite limit at infinity.

Example:

The line y = 3 is a horizontal asymptote for the function k(x)=(3x2+1)/(x2+x)k(x) = (3x^2+1)/(x^2+x), meaning the function's graph flattens out towards y = 3 as x gets very large or very small.

Horizontal Asymptote

Criticality: 3

A horizontal line that the graph of a function approaches as the input (x) tends towards positive or negative infinity.

Example:

The function f(x)=2x+1x3f(x) = \frac{2x+1}{x-3} has a horizontal asymptote at y=2y=2, indicating that as xx becomes very large or very small, the function's values get arbitrarily close to 2.

I

Indeterminate forms

Criticality: 3

Expressions like $\frac{0}{0}$ or $\frac{\infty}{\infty}$ that arise when evaluating limits by direct substitution, indicating that further analysis or manipulation is required to find the actual limit.

Example:

When trying to find limx0sinxx\lim_{x\to 0} \frac{\sin x}{x}, direct substitution yields the indeterminate form 00\frac{0}{0}, requiring L'Hopital's Rule or series expansion.

Infinite Limit

Criticality: 3

An infinite limit occurs when the values of a function become unbounded (either positively or negatively) as the input variable approaches a specific finite value.

Example:

As x approaches 0, the function f(x)=1/x2f(x) = 1/x^2 demonstrates an infinite limit, shooting up towards positive infinity.

Infinite Limits

Criticality: 3

Limits where the function's value increases or decreases without bound (tends to $\infty$ or $-\infty$) as the input approaches a certain value.

Example:

The function f(x)=1/xf(x) = 1/x has infinite limits as xx approaches 0, tending to \infty from the right and -\infty from the left.

Infinite Limits of Quotients

Criticality: 3

Rules for determining the infinite behavior of a quotient of functions when the numerator approaches a non-zero constant and the denominator approaches zero.

Example:

If limx0f(x)=5\lim_{x \to 0} f(x) = 5 and limx0g(x)=0\lim_{x \to 0} g(x) = 0, the infinite limits of quotients property helps determine if limx0f(x)g(x)\lim_{x \to 0} \frac{f(x)}{g(x)} is \infty or -\infty based on the sign of g(x)g(x).

L

Left-hand limit

Criticality: 2

The value a function approaches as the input variable approaches a specific point from values less than that point.

Example:

When analyzing f(x)=x/xf(x) = |x|/x, the left-hand limit as x0x \to 0^- is -1.

Limit

Criticality: 3

The value that a function or sequence 'approaches' as the input or index approaches some value. It describes the behavior of a function near a point, rather than at the point itself.

Example:

The limit of f(x)=x29x3f(x) = \frac{x^2 - 9}{x - 3} as xx approaches 3 is 6, even though the function is undefined at x=3x=3.

Limit

Criticality: 3

The value that a function approaches as its input approaches some specific value.

Example:

For the function f(x)=x+2f(x) = x+2, the limit as xx approaches 3 is 5, meaning the function's output gets arbitrarily close to 5 as the input gets close to 3.

Limit

Criticality: 3

The value that a function approaches as its input approaches a certain point, without necessarily reaching that value.

Example:

For the function f(x)=x2f(x) = x^2, the limit as x approaches 3 is 9, meaning as x gets infinitesimally close to 3, f(x)f(x) gets arbitrarily close to 9.

Limit at Infinity

Criticality: 3

A limit at infinity describes the long-term behavior of a function, specifically what value the function's output approaches as its input variable increases or decreases without bound.

Example:

For the function h(x)=(2x+1)/xh(x) = (2x+1)/x, the limit at infinity as x approaches positive infinity is 2, showing the function stabilizes at that value.

Limit at infinity

Criticality: 3

The value a function approaches as its input variable grows infinitely large (positive or negative).

Example:

For f(x)=1xf(x) = \frac{1}{x}, the limit at infinity as xx \to \infty is 0, indicating the function approaches the x-axis.

Limit of 1/x^n as x Approaches 0

Criticality: 2

Describes how the function $1/x^n$ behaves as x approaches 0 from the positive or negative side, resulting in positive or negative infinity depending on 'n' being even or odd.

Example:

When analyzing the behavior of y=1/x2y = 1/x^2 near x=0x=0, the limit of 1/x^n as x approaches 0 tells us it tends to \infty from both sides because n=2n=2 is even.

Limit of a Composite Function

Criticality: 3

If the outer function is continuous at the limit of the inner function, the limit of a composite function can be found by evaluating the outer function at the limit of the inner function.

Example:

For limx0sin(x2)\lim_{x \to 0} \sin(x^2), since sin(x)\sin(x) is continuous, you can find limx0x2=0\lim_{x \to 0} x^2 = 0 and then evaluate sin(0)\sin(0), applying the limit of a composite function.

Limit of a Constant Function

Criticality: 2

The limit of a constant function as the input approaches any value 'a' is always the constant itself.

Example:

If you're calculating the speed of light, which is a constant, its limit of a constant function as time approaches any point is still the speed of light.

Limit of a Multiple of a Function

Criticality: 3

The limit of a constant multiplied by a function is the constant multiplied by the limit of the function.

Example:

If limx1f(x)=5\lim_{x \to 1} f(x) = 5, then limx1(4f(x))\lim_{x \to 1} (4f(x)) uses the limit of a multiple of a function to become 4×5=204 \times 5 = 20.

Limit of a Product of Functions

Criticality: 3

The limit of the product of two functions is the product of their individual limits, assuming both limits exist.

Example:

When evaluating limx3(xsinx)\lim_{x \to 3} (x \cdot \sin x), you can use the limit of a product of functions to multiply limx3x\lim_{x \to 3} x by limx3sinx\lim_{x \to 3} \sin x.

Limit of a Quotient of Functions

Criticality: 3

The limit of a quotient of two functions is the quotient of their individual limits, provided the limit of the denominator is not zero.

Example:

To find limx1x2+1x+1\lim_{x \to 1} \frac{x^2+1}{x+1}, you apply the limit of a quotient of functions, calculating the limit of the numerator and denominator separately.

Limit of a Sum or Difference of Functions

Criticality: 3

The limit of a sum or difference of functions is the sum or difference of their individual limits, provided those limits exist.

Example:

To find limx0(x2+cosx)\lim_{x \to 0} (x^2 + \cos x), you can apply the limit of a sum or difference of functions to evaluate limx0x2\lim_{x \to 0} x^2 and limx0cosx\lim_{x \to 0} \cos x separately.

Limit of the Power of a Function

Criticality: 2

The limit of a function raised to a power is the limit of the function raised to that same power, for any real number power.

Example:

If you need to find limx2(x3)2\lim_{x \to 2} (x^3)^2, you can first find limx2x3\lim_{x \to 2} x^3 and then square the result, using the limit of the power of a function.

Limit properties

Criticality: 3

Rules that allow algebraic manipulation of limits to simplify complex functions and determine their behavior.

Example:

Using limit properties, we can break down limx2(3x24x+5)\lim_{x \to 2} (3x^2 - 4x + 5) into simpler parts like limx2(3x2)\lim_{x \to 2} (3x^2) and limx2(4x)\lim_{x \to 2} (4x).

Limits

Criticality: 3

The value that a function approaches as its input values get arbitrarily close to a certain point. They are fundamental to calculus, defining derivatives and integrals.

Example:

When analyzing the function f(x)=sin(x)xf(x) = \frac{\sin(x)}{x}, the limit as x approaches 0 is 1, even though the function itself is undefined at x=0.

N

Nonexistent Limits

Criticality: 3

A situation where a function does not approach a single, finite value as its input approaches a certain point. This can occur if the function is unbounded, oscillates, or has unequal one-sided limits.

Example:

The function f(x)=tan(x)f(x) = \tan(x) has a nonexistent limit as x approaches π/2\pi/2 because the function becomes unbounded.

O

One-Sided Limit

Criticality: 3

The value a function approaches as the input variable approaches a specific point from either the left (values less than the point) or the right (values greater than the point).

Example:

For a piecewise function, checking the one-sided limit as x0+x \to 0^+ for f(x)=x2f(x) = x^2 would give 0, while x0x \to 0^- for f(x)=x1f(x) = x-1 would give -1.

One-sided Limits

Criticality: 3

The value a function approaches as its input approaches a specific point from either the left (below) or the right (above) side only.

Example:

For a piecewise function like f(x)=x/xf(x) = |x|/x, the one-sided limit as x approaches 0 from the left is -1, and from the right is 1.

One-sided limit

Criticality: 2

The value a function approaches as the input variable approaches a specific point from either the left side (values less than the point) or the right side (values greater than the point).

Example:

For f(x)=1/xf(x) = 1/x, the one-sided limit as x approaches 0 from the right (xo0+x o 0^+) is positive infinity, while from the left (xo0x o 0^-) it's negative infinity.

Oscillates

Criticality: 2

Describes a function that fluctuates rapidly between different values without settling on a single value as the input approaches a certain point.

Example:

The function f(x)=sin(1/x)f(x) = \sin(1/x) oscillates infinitely many times between -1 and 1 as x approaches 0, preventing a limit from existing.

P

Piecewise Function

Criticality: 3

A function defined by multiple sub-functions, each applicable over a specific interval of the domain.

Example:

A common example of a piecewise function is f(x)={x+1,x<0x2,x0f(x) = \begin{cases} x+1, & x < 0 \\ x^2, & x \geq 0 \end{cases}, which behaves differently on either side of x=0x=0.

Q

Quotient

Criticality: 1

The result obtained when one number or quantity is divided by another.

Example:

In the expression x24x2\frac{x^2 - 4}{x - 2}, the entire fraction represents a quotient of two polynomial expressions.

Quotient (function)

Criticality: 1

A function expressed as the ratio of two other functions, where vertical asymptotes often occur at points where the denominator becomes zero.

Example:

The function f(x)=x2+1x4f(x) = \frac{x^2+1}{x-4} is a quotient function, and its denominator becoming zero at x=4x=4 suggests a potential vertical asymptote.

R

Reciprocal

Criticality: 2

The multiplicative inverse of a number or expression, obtained by dividing 1 by that number or expression.

Example:

The reciprocal of x2x^2 is 1x2\frac{1}{x^2}, which is useful when finding limits at infinity.

Right-hand limit

Criticality: 2

The value a function approaches as the input variable approaches a specific point from values greater than that point.

Example:

For the function f(x)=x/xf(x) = |x|/x, the right-hand limit as x0+x \to 0^+ is 1.

S

Simplifying (to find limits)

Criticality: 3

A technique used when direct substitution yields an indeterminate form, involving algebraic manipulation (like factoring and canceling) to transform the function into an equivalent form where substitution works.

Example:

To find limx2x24x2\lim_{x\to 2} \frac{x^2-4}{x-2}, you can use simplifying by factoring the numerator to (x2)(x+2)(x-2)(x+2), canceling (x2)(x-2), and then substituting into x+2x+2 to get 4.

Squeeze Theorem

Criticality: 3

A mathematical theorem used to determine the limit of a function by comparing it to two other functions whose limits are known and equal at a specific point.

Example:

If you can show that g(x)f(x)h(x)g(x) \le f(x) \le h(x) and both g(x)g(x) and h(x)h(x) approach 5 as xx approaches 2, then by the Squeeze Theorem, f(x)f(x) must also approach 5.

Substitution

Criticality: 3

A direct method to evaluate limits by replacing the variable with the value it approaches, primarily effective for continuous functions.

Example:

To find the limit of f(x)=2x+5f(x) = 2x + 5 as xx approaches 3, you can use substitution to get 2(3)+5=112(3) + 5 = 11.

Surds

Criticality: 1

Expressions that contain irrational roots, typically square roots, that cannot be simplified to a rational number.

Example:

Numbers like 2\sqrt{2}, 7\sqrt{7}, or 12\sqrt{12} (which simplifies to 232\sqrt{3}) are examples of surds.

T

Table (of values)

Criticality: 2

An organized display of numerical data showing function outputs for various inputs, used to estimate the behavior of a function near a specific point.

Example:

By examining a table of values for f(x)=sinxxf(x) = \frac{\sin x}{x} as xx gets closer to 0, you can estimate that its limit is 1.

Trigonometric Identity

Criticality: 2

An equation involving trigonometric functions that is true for all values of the variables for which the functions are defined. They are essential tools for simplifying expressions and solving equations.

Example:

To simplify 1cos2xx2\frac{1 - \cos^2 x}{x^2} for a limit problem, you would use the trigonometric identity sin2x+cos2x=1\sin^2 x + \cos^2 x = 1 to replace 1cos2x1 - \cos^2 x with sin2x\sin^2 x.

Trigonometric Limit Theorem ((cos x - 1) / x)

Criticality: 2

A fundamental theorem stating that the limit of $\frac{\cos x - 1}{x}$ as $x$ approaches 0 is 0. This theorem is often used in conjunction with other limit properties.

Example:

When faced with limxo01cos4xx\lim_{x o 0} \frac{1 - \cos 4x}{x}, you can rearrange it to utilize this specific Trigonometric Limit Theorem.

Trigonometric Limit Theorem (sin x / x)

Criticality: 3

A fundamental theorem stating that the limit of $\frac{\sin x}{x}$ as $x$ approaches 0 is 1. This is crucial for evaluating many indeterminate trigonometric forms.

Example:

To find limxo0sin5x2x\lim_{x o 0} \frac{\sin 5x}{2x}, you can manipulate the expression to apply the Trigonometric Limit Theorem for sinxx\frac{\sin x}{x}.

Two-sided Limits

Criticality: 3

The value a function approaches as its input approaches a specific point from both the left and the right sides. For this limit to exist, the corresponding one-sided limits must be equal.

Example:

If a function smoothly approaches 5 as x gets closer to 2 from both directions, then its two-sided limit at x=2 is 5.

U

Unbounded

Criticality: 2

Describes a function whose values increase or decrease without limit (to positive or negative infinity) as the input approaches a certain point.

Example:

The function f(x)=1/x2f(x) = 1/x^2 is unbounded as x approaches 0, shooting up towards positive infinity.

Unbounded

Criticality: 2

Describes a function's behavior where its output values increase or decrease without limit, often occurring near vertical asymptotes.

Example:

As xx approaches 0, the function f(x)=1x2f(x) = \frac{1}{x^2} becomes unbounded, meaning its values shoot up towards positive infinity.

V

Vertical Asymptote

Criticality: 3

A vertical line that the graph of a function approaches but never touches or intersects as the input variable approaches a certain value where the function has an infinite limit.

Example:

The line x = 2 is a vertical asymptote for the function g(x)=1/(x2)g(x) = 1/(x-2), indicating the function's values become unbounded near x = 2.

Vertical Asymptote

Criticality: 3

A vertical line where a function's graph approaches infinity or negative infinity as the input (x) approaches a specific finite value.

Example:

The function f(x)=1x5f(x) = \frac{1}{x-5} has a vertical asymptote at x=5x=5, because the function's values become infinitely large or small as xx gets closer to 5.