# LIMITS OF FUNCTIONS.

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LIMITS OF FUNCTIONS

INFINITE LIMITS; VERTICAL AND HORIZONTAL ASYMPTOTES; SQUEEZE THEOREM
OBJECTIVES: define infinite limits; illustrate the infinite limits ; and use the theorems to evaluate the limits of functions. determine vertical and horizontal asymptotes define squeeze theorem

DEFINITION: INFINITE LIMITS
Sometimes one-sided or two-sided limits fail to exist because the value of the function increase or decrease without bound. For example, consider the behavior of for values of x near 0. It is evident from the table and graph in Fig that as x values are taken closer and closer to 0 from the right, the values of are positive and increase without bound; and as x-values are taken closer and closer to 0 from the left, the values of are negative and decrease without bound.

In symbols, we write Note: The symbols here are not real numbers; they simply describe particular ways in which the limits fail to exist. Thus it is incorrect to write

Figure (p. 74)

1.1.4 (p. 75) Infinite Limits (An Informal View)

Figure 1.1.2 illustrate graphically the limits for rational functions of the form .
Figure (p. 84)

EXAMPLE: Evaluate the following limits:

SUMMARY:

EXAMPLE

VERTICAL AND HORIZONTAL ASYMPTOTES

DEFINITION: The line is a vertical asymptote of the graph of the function if at least one of the following statement is true:

The following figures illustrate the vertical asymptote .
x=a x=a

The following figures illustrate the vertical asymptote .
x=a x=a

DEFINITION: The line is a horizontal asymptote of the graph of the function if either

The following figures illustrate the horizontal asymptote
y=b y=b

The following figures illustrate the horizontal asymptote
y=b y=b

Determine the horizontal and vertical asymptote of
the function and sketch the graph. a. Vertical Asymptote: Equate the denominator to zero to solve for the vertical asymptote. b. Horizontal Asymptote: Divide both the numerator and the denominator by the highest power of x to solve for the horizontal asymptote. Evaluate the limit as x approaches 2

HA:y=0 VA: x=2

Determine the horizontal and vertical asymptote of
the function and sketch the graph. a. Vertical Asymptote: b. Horizontal Asymptote:

HA:y=2 VA:x=3 o

SQUEEZE THEOREM

LIMITS OF FUNCTIONS USING THE SQUEEZE PRINCIPLE
The Squeeze Principle is used on limit problems where the usual algebraic methods (factoring, conjugation, algebraic manipulation, etc.) are not effective. However, it requires that you be able to ``squeeze'' your problem in between two other ``simpler'' functions whose limits are easily computable and equal. The use of the Squeeze Principle requires accurate analysis, algebra skills, and careful use of inequalities. The method of squeezing is used to prove that f(x)→L as x→c by “trapping or squeezing” f between two functions, g and h, whose limits as x→c are known with certainty to be L.

SQUEEZE PRINCIPLE :

Theorem (p. 123) Figure (p. 123)

EXAMPLE: SOLUTION:

EXERCISES: Evaluate the following limits: