Logarithmic Functions

Vocabulary

asymptote

line that a graph approaches as one of the variables approaches infinity or negative infinity

change of base rule

rule that states that a logarithm of a number in base bb can be changed to base aa by dividing the logarithm of the number in base aa by the logarithm of bb in base aa

common logarithm

logarithm with base 10, or the exponent to which 10 is raised to equal a given number; written as logx\log{x}, where xx is the given number

exponent

number that indicates how many times a base is multiplied by itself and shown by a raised number, such as 434^{3}

input

value in the domain of a function

inverse function

result of switching the inputs and outputs of a function when the result is also a function. The composition of a function and its inverse is the identity function.

logarithm

exponent xx to which a base bb is raised to produce a given number yy, written as:
x=logbyx=\log_b{y}

logarithmic function

function, where b>0b>0 and b1b\neq 1, written in the form:
f(x)=logbxf(x)=\log_b{x}

natural logarithm

logarithm with base ee, where e2.718281845e\approx2.718281845\dots, or the exponent to which ee must be raised to equal a given number; written as lnx\ln{x}, where xx is the given number

output

value in the range of a function

parent function

function of a certain type that has the simplest algebraic rule

power rule of logarithms

rule that states that the logarithm of a power is equal to the product of the exponent and the logarithm of the base

product rule of logarithms

rule that states that the logarithm of a product is equal to the sum of the logarithms of the factors

quotient rule of logarithms

rule that states that the logarithm of a quotient is equal to the difference of the logarithm of the dividend and the logarithm of the divisor