Coordinate Geometry
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Geometry › Coordinate Geometry
Define a function as follows:
Give the vertical aysmptote of the graph of .
The graph of does not have a vertical asymptote.
Explanation
Since any number, positive or negative, can appear as an exponent, the domain of the function is the set of all real numbers; in other words,
is defined for all real values of
. It is therefore impossible for the graph to have a vertical asymptote.
Define a function as follows:
Give the horizontal aysmptote of the graph of .
Explanation
The horizontal asymptote of an exponential function can be found by noting that a positive number raised to any power must be positive. Therefore, and
for all real values of
. The graph will never crosst the line of the equatin
, so this is the horizontal asymptote.
What is the domain of ?
all real numbers
Explanation
The domain of the function specifies the values that can take. Here,
is defined for every value of
, so the domain is all real numbers.
Define
What is the natural domain of ?
Explanation
The radical in and of itself does not restrict the domain, since every real number has a real cube root. However, since the expression is in a denominator, it cannot be equal to zero, so the domain excludes the value(s) for which
27 is the only number excluded from the domain.
Give the -coordinate(s) of the
-intercept(s) of the graph of the function
The graph of has no
-intercept.
Explanation
The -intercept(s) of the graph of
are the point(s) at which it intersects the
-axis. The
-coordinate of each is 0; their
-coordinate(s) are those value(s) of
for which
, so set up, and solve for
, the equation:
Add to both sides:
Multiply both sides by 2:
,
the correct choice.
Give the -coordinate of the
-intercept of the graph of the function
The graph of has no
-intercept.
Explanation
The -intercept of the graph of
is the point at which it intersects the
-axis. Its
-coordinate is 0,; its
-coordinate is
, which can be found by substituting 0 for
in the definition:
However, does not have a real value. Therefore, the graph of
has no
-intercept.
The chord of a central angle of a circle with area
has what length?
Explanation
The radius of a circle with area
can be found as follows:
The circle, the central angle, and the chord are shown below:

By way of the Isosceles Triangle Theorem, can be proved equilateral, so
, the correct response.
Which of the following are the equations of the vertical asymptotes of the graph of ?
(a)
(b)
(b) only
(a) only
Both (a) and (b)
Neither (a) nor (b)
Explanation
The vertical asymptote(s) of the graph of a rational function such as can be found by evaluating the zeroes of the denominator after the rational expression is reduced.
First, factor the denominator. It is a quadratic trinomial with lead term , so look to "reverse-FOIL" it as
by finding two integers with sum 6 and product 5. By trial and error, these integers can be found to be 1 and 5, so
Therefore, can be rewritten as
Set the denominator equal to 0 and solve for :
By the Zero Factor Principle,
or
Therefore, the binomial factor can be cancelled, and the function can be rewritten as
If , then
, so the denominator has only this one zero, and the only vertical asymptote is the line of the equation
.
True or false: The graph of has as a vertical asymptote the graph of the equation
.
False
True
Explanation
The vertical asymptote(s) of the graph of a rational function such as can be found by evaluating the zeroes of the denominator after the rational expression is reduced.
First, factor the numerator. It is a quadratic trinomial with lead term , so look to factor
by using the grouping technique. We try finding two integers whose sum is and whose product is
; with some trial and error we find that these are
and
, so:
Break the linear term:
Regroup:
Factor the GCF twice:
Therefore, can be rewritten as
Cancel the common factor from both halves; the function can be rewritten as
Set the denominator equal to 0 and solve for :
The graph of therefore has one vertical asymptotes, the line of the equations
. The line of the equation
is not a vertical asymptote.
Give the domain of the function
The set of all real numbers
Explanation
The function is defined for those values of
for which the radicand is nonnegative - that is, for which
Subtract 25 from both sides:
Since the square root of a real number is always nonnegative,
for all real numbers . Since the radicand is always positive, this makes the domain of
the set of all real numbers.