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Clicker Question 1. What is the lim x 0- f ( x ) for the function pictured on the board? A. 2 B. 0 C. -2 D. Does not exist. Clicker Question 2. What is the lim x 0 f ( x ) for the function pictured on the board? A. 2 B. 0 C. -2 D. Does not exist.
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Clicker Question 1 • What is the limx 0-f (x ) for the function pictured on the board? • A. 2 • B. 0 • C. -2 • D. Does not exist
Clicker Question 2 • What is the limx 0f (x ) for the function pictured on the board? • A. 2 • B. 0 • C. -2 • D. Does not exist
Limits at Infinity and Global Asymptotes (2/6/09) • By the “limit at infinity of a function f″ we mean what f ′s value gets near as the input x goes out the positive (+) or negative (-) horizontal axis. • We write limx f (x ) or limx - f (x ). • It’s possible that the answer can be a number, or be or -, or not exist.
Examples • limx 1/(x + 4) = • limx x + 4 = • limx -x + 4 = • limx ex = • limx - ex = • limx (2x +3)/(x – 1) = • limx arctan(x ) =
Clicker Question 3 • What is limx x / (x2 +5) ? • A. + • B. - • C. 0 • D. 1 • E. Does not exist
Clicker Question 4 • What is limx x 2/ (x2 +5) ? • A. + • B. - • C. 0 • D. 1 • E. Does not exist
Clicker Question 5 • What is limx - x 3/ (x2 +5) ? • A. + • B. - • C. 0 • D. 1 • E. Does not exist
Nonexistent Limits at Infinity? • Is it possible for a function to have no limit (including not + nor -)? • If so, what is an example?
Global Asymptotes • When limx f (x ) is a finite number a, then the graph of f has a horizontal asymptote, the line y = a . • We can also call this a global asymptote since it describes the global (as opposed to local) behavior of f . • But global asymptotes need not be horizontal lines nor even straight lines!
Examples • f (x ) = x /(x – 2) has a horizontal global asymptote. What is it? • g (x ) = x2 / (x – 2) has a diagonal global asymptote. What is it? • h (x ) = x3 / (x – 2) has a parabolic global asymptote. What is it?
Assignment • Monday we will have Lab #2 on power functions, polynomial functions, rational functions, and local and global behavior. • Hand-in #1 is due at 4:45 on Tuesday. • For Wednesday, please read Section 2.6 through page 137 and do Exercises 1, 3, 9, 15, 19, 28, 31, 35, 39 and 43.