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Glossary

C

Chain Rule

Criticality: 3

A rule used to differentiate composite functions, stating that the derivative of $f(g(x))$ is $f'(g(x)) \cdot g'(x)$.

Example:

To find the derivative of y=sin(x2)y = \sin(x^2), you'd apply the Chain Rule to get y=cos(x2)2xy' = \cos(x^2) \cdot 2x.

Constant Multiple Rule

Criticality: 2

A differentiation rule stating that the derivative of a constant times a function is the constant times the derivative of the function.

Example:

If f(x)=5x3f(x) = 5x^3, then f(x)=5(3x2)=15x2f'(x) = 5 \cdot (3x^2) = 15x^2, applying the Constant Multiple Rule.

D

Derivative of cos x

Criticality: 3

The rate of change of the cosine function, which is the negative of the sine function.

Example:

When modeling the oscillation of a spring with x(t)=costx(t) = \cos t, the velocity of the spring is v(t)=sintv(t) = -\sin t, found by taking the Derivative of cos x.

Derivative of e^x

Criticality: 3

The rate of change of the natural exponential function, which is unique in that it is equal to itself.

Example:

If a population grows exponentially according to P(t)=100etP(t) = 100e^t, then the rate of population growth, P(t)P'(t), is also 100et100e^t, demonstrating the special property of the Derivative of e^x.

Derivative of ln x

Criticality: 3

The rate of change of the natural logarithm function, which is the reciprocal of x.

Example:

To find the rate at which a quantity modeled by Q(x)=lnxQ(x) = \ln x changes, you'd calculate Q(x)=1xQ'(x) = \frac{1}{x}, using the rule for the Derivative of ln x.

Derivative of sin x

Criticality: 3

The rate of change of the sine function, which is the cosine function.

Example:

If a particle's position is given by s(t)=sints(t) = \sin t, its velocity is v(t)=costv(t) = \cos t, meaning its instantaneous rate of change of position is the Derivative of sin x.

P

Power Rule

Criticality: 3

A fundamental differentiation rule used to find the derivative of functions in the form $x^n$, where the derivative is $nx^{n-1}$.

Example:

To find the rate of change of the volume of a sphere with respect to its radius, V(r)=43πr3V(r) = \frac{4}{3}\pi r^3, you'd use the Power Rule to get V(r)=4πr2V'(r) = 4\pi r^2.

Product Rule

Criticality: 2

A rule for differentiating the product of two functions, given by $(uv)' = u'v + uv'$.

Example:

If you need to find the derivative of f(x)=x2sinxf(x) = x^2 \sin x, you would use the Product Rule to get f(x)=2xsinx+x2cosxf'(x) = 2x \sin x + x^2 \cos x.

Q

Quotient Rule

Criticality: 2

A rule for differentiating the quotient of two functions, given by $(\frac{u}{v})' = \frac{u'v - uv'}{v^2}$.

Example:

To differentiate g(x)=exxg(x) = \frac{e^x}{x}, you'd apply the Quotient Rule to find g(x)=exxex1x2g'(x) = \frac{e^x \cdot x - e^x \cdot 1}{x^2}.

S

Second Derivative

Criticality: 3

The derivative of the first derivative of a function, representing the rate of change of the slope of the tangent line or the concavity of the function.

Example:

If s(t)s(t) is position, s(t)s'(t) is velocity, and s(t)s''(t) is acceleration, which is the Second Derivative of position.

T

Tangent Line

Criticality: 3

A straight line that touches a curve at a single point and has the same slope as the curve at that point, representing the instantaneous rate of change.

Example:

To find the equation of the Tangent Line to f(x)=x2f(x) = x^2 at x=2x=2, you'd find f(2)=4f(2)=4 and f(2)=4f'(2)=4, leading to y4=4(x2)y-4=4(x-2).

Trig Identities

Criticality: 1

Equations involving trigonometric functions that are true for all values of the variables for which the functions are defined, often used to simplify expressions before differentiation.

Example:

Before differentiating sin2x+cos2x\sin^2 x + \cos^2 x, you could simplify it to 11 using a fundamental Trig Identity, making its derivative 00.