Intro to Graphing Logs

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Chapter Introduction:

Chapter Introduction Exponential Functions How do we solve a x = b? How do we graph f(x)=a x ? What are the properties of logarithms? How do we simplify logarithms? How do we solve logarithms?

Reminder of Transformations:

Reminder of Transformations What does each of these transformations do to f(x)? f(x)+k Move the function up k. f(x+h) Move the function left h. f(-x) Reflect the function across the y axis f -1 (x) Reflects the function over the y=x line.

Here is a graph of f(x)=2x:

Here is a graph of f(x)=2 x

Transformations:

Transformations If f(x)=2 x graph… f(x)+3 f(x+3) f(-x) f -1 (x) Uhhh, how do we do that?

Inverse of an exponential function:

Inverse of an exponential function If f(x)=2 x The inverse of f(x) is not Remember that the inverse of multiplication -> division, addition -> subtraction What about exponentiation? The inverse of exponentiation is a logarithm.

Graphs:

Graphs A graph of 2 x and log 2 (x)

First section:

First section Before we get into logarithms lets look closer at exponential functions. Graph these functions one at a time . f(x) = 2 x <- almost the parent function. g(x) = .5 x h(x)=2 -x What is happening here?

2x:

2 x What happens as x gets very negative? Remember that a negative exponent flips the term to the other side of a fraction. 2 -100 = which is a very small number but still positive What happens as x gets very positive? 2 100 is a huge number

:

What happens as x gets very negative? is a very large number What happens as x gets very positive? is a very small number but still positive.

2-x:

2 -x 2 -x is the same thing as So their graphs are identical. We must be aware of the base that we are dealing with. When the base is greater than 1 and the exponent is positive the function grows to the right When the base is between 0 and 1 it grows to the left

An obvious question.:

An obvious question. What if the base is negative or is between -1 and 0? Try it on your calc.