1/13/2016
Warm Up
Solve:
1. log x = −2
4.3 part 2 – Graphing
Logarithmic Functions
2. log x 27 = 3
Objective: TSW graph logarithmic
functions and find the domain and
range of the function.
Let’s Review an Exponential Function First
y = abx-h + k
a = start amount
If there is no “a” then
a=1
h = moves the
graph left or
right
k = moves the
graph up or
down
b = growth/decay factor
b is ALWAYS the number
with the exponent
Domain and Range…
Since a logarithmic equation is the inverse of an
exponential…the domain and range flip flop!
Graphing a Logarithmic Function is
Similar, but turned sideways…
We still have a, b, h, and k…we just are using the
k = moves the
x axis to graph our main points now.
y = a log b ( x − h) + k
a = 1 if there is no “a”
graph up or
down
h = moves the
graph left or
right
b = whether the graph
Increases upwards or
Downwards. If b>1 goes up
If b is a fraction goes down.
Examples, Graph and State the Domain
and Range.
2. y = log 1 / 8 x
1. y = log 2 x
y
y
Domain:
x
x
Range:
1
1/13/2016
Examples, Graph and State the Domain
and Range.
3.
4.
y = log 3 ( x − 2)
y
y = log 1 / 2 ( x + 1) − 5
Homework…
4.3 part 2 page 442 #’s 31,33,34,36,37,39,43,45
y
x
x
2