Math 1F03 – Lecture Exponential Functions 1.6 Inverse Functions and Logarithms 2.2 Introduction to Limits

1.5 Exponential Functions An exponential function is a function of the form where is a positive real number called the base and is a variable called the exponent. Domain: Range:

Graphs of Exponential Functions When a>1, the function is increasing. When a<1, the function is decreasing. y=0 is a horizontal asymptote

Transformation of an Exponential Function Graph Recall: is a special irrational number between 2 and 3 that is commonly used in calculus Approximation:

Laws of Exponents Examples:

Exponential Models P. 57 #24. Suppose you are offered a job that lasts one month. Which of the following methods of payment do you prefer? I.One million dollars at the end of the month. II.One cent on the first day of the month, two cents on the second day, four cents on the third day, and, in general, cents on the nth day.

1.6 Inverse Functions The function is the inverse of if and. Each of and undoes the action of the other. Diagram: Some simple examples:

What Functions Have Inverses? A function has an inverse if and only if it is a one-to-one function. A function f is one-to-one if for every y-value in the range of f, there is exactly one x-value in the domain of f such that y=f(x). Examples:

Horizontal Line Test If every horizontal line intersects the graph of a function in at most one point, then the graph represents a one-to-one function.

Finding the Inverse of a Function Algorithm: 1.Write the equation y=f(x). 2.Solve for x in terms of y. 3.Replace x by (x) and y by x. Note: The domain and range are interchanged Example: Find the inverse of the following functions. State domain and range.

Graphs of and The graph of is the graph of reflected in the line Points (x,y) on become the points (y,x) on Example: Given sketch and.

f

1.6 Logarithmic Functions The inverse of an exponential function is a logarithmic function, i.e. Cancellation equations: In general:For exponentials & logarithms:

Understanding Logarithm Notation

Graphs of Logarithmic Functions Recall: For inverse functions, the domain and range are interchanged and their graphs are reflections in the line Example: Graph

Graphs of Logarithmic Functions

The Natural Logarithm Domain: Range: Graph: The graph increases from negative infinity near x=0 (vertical asymptote) and rises more and more slowly as x becomes larger. Note: and

Transformation of a Log Function Example: Graph State the domain.

Laws of Logs For x,y>0 and p any real number: Example: Simplify, if possible. (a)(b) (c) (d)

Some Exercises Solve the following equations for x. (a) (b) (c)(d)

2.2 The Limit of a Function Notations: means that the y-value of the function AT x=2 is 5 means that the y-value of the function NEAR x=2 is NEAR 4

The Limit of a Function

Limit of a Function Some examples: Note: f may or may not be defined AT x=a. Limits are only concerned with how f is defined NEAR a.

Left-Hand and Right-Hand Limits means as from the left means as from the right ** The full limit exists if and only if the left and right limits both exist (equal a real number) and are the same value.

Left-Hand and Right-Hand Limits For each function below, determine the value of the limit or state that it does not exist.

Evaluating Limits We can evaluate the limit of a function in 3 ways: 1.Graphically 2.Numerically 3.Algebraically

Evaluating Limits Example: Evaluate graphically.

Evaluating Limits Example: Use a table of values to estimate the value of xf(x) undefined

Evaluating Limits Example: Use a table of values to estimate the value of xf(x) undefined

Infinite Limits

Example: Determine the infinite limit. #30. #34. Note: Since the values of these functions do not approach a real number L, these limits do not exist.

Vertical Asymptotes Example: Basic functions we know that have VAs: