All Advanced Geometry Resources
Example Questions
Example Question #11 : How To Graph A Logarithm
Let be the point of intersection of the graphs of these two equations:
Evaluate .
The system has no solution.
Substitute and for and , respectively, and solve the resulting system of linear equations:
Multiply the first equation by 2, and the second by 3, on both sides, then add:
Back-solve:
We need to find both and to ensure a solution exists. By substituting back:
and
We check this solution in both equations:
- true.
- true.
is the solution, and , the correct choice.
Example Question #76 : Graphing
The graph of function has vertical asymptote . Which of the following could give a definition of ?
Given the function , the vertical asymptote can be found by observing that a logarithm cannot be taken of a number that is not positive. Therefore, it must hold that , or, equivalently, and that the graph of will never cross the vertical line . That makes the vertical asymptote, so it follows that the graph with vertical asymptote will have in the position. The only choice that meets this criterion is
Example Question #12 : How To Graph A Logarithm
The graph of a function has -intercept . Which of the following could be the definition of ?
All of the other choices are correct.
All of the other choices are correct.
All of the functions are of the form . To find the -intercept of such a function, we can set and solve for :
Since we are looking for a function whose graph has -intercept , the equation here becomes , and we can examine each of the functions by finding the value of .
:
:
:
:
All four choices fit the criterion.
Example Question #77 : Graphing
The graph of a function has -intercept . Which of the following could be the definition of ?
All of the functions take the form
for some integer . To find the choice that has -intercept , set and , and solve for :
In exponential form:
The correct choice is .
Example Question #13 : How To Graph A Logarithm
Define a function as follows:
Give the -intercept of the graph of .
Set and evaluate to find the -coordinate of the -intercept.
Rewrite in exponential form:
.
The -intercept is .
Example Question #14 : How To Graph A Logarithm
Define functions and as follows:
Give the -coordinate of a point at which the graphs of the functions intersect.
The graphs of and do not intersect.
The graphs of and do not intersect.
Since , the definition of can be rewritten as follows:
Since , the definition of can be rewritten as follows:
First, we need to find the -coordinate of the point at which the graphs of and meet by setting
Since the common logarithms of the two polynomials are equal, we can set the polynomials themselves equal, then solve:
However, if we evaluate , the expression becomes
,
which is undefined, since a negative number cannot have a logarithm.
Consequently, the two graphs do not intersect.
Example Question #15 : How To Graph A Logarithm
The graph of a function has -intercept . Which of the following could be the definition of ?
None of the other responses gives a correct answer.
All of the functions are of the form . To find the -intercept of a function , we can set and solve for :
.
Since we are looking for a function whose graph has -intercept , the equation here becomes , and we can examine each of the functions by finding the value of and seeing which case yields this result.
:
:
:
:
The graph of has -intercept and is the correct choice.
Example Question #16 : How To Graph A Logarithm
Define a function as follows:
A line passes through the - and -intercepts of the graph of . Give the equation of the line.
The -intercept of the graph of can befound by setting and solving for :
Rewritten in exponential form:
The -intercept of the graph of is .
The -intercept of the graph of can be found by evaluating
The -intercept of the graph of is .
If and are the - and -intercepts, respectively, of a line, the slope of the line is . Substituting and , this is
.
Setting and in the slope-intercept form of the equation of a line:
Example Question #17 : How To Graph A Logarithm
Define functions and as follows:
Give the -coordinate of a point at which the graphs of the functions intersect.
The graphs of and do not intersect.
Since , the definition of can be rewritten as follows:
.
Find the -coordinate of the point at which the graphs of and meet by setting
Since the common logarithms of the two polynomials are equal, we can set the polynomials themselves equal, then solve:
The quadradic trinomial can be "reverse-FOILed" by noting that 2 and 6 have product 12 and sum 8:
Either , in which case
or
, in which case
Note, however, that we can eliminate as a possible -value, since
,
an undefined quantity since negative numbers do not have logarithms.
Since
and
,
is the correct -value, and is the correct -value.
Example Question #101 : Advanced Geometry
This graph shows the graph of . The blue point has an -coordinate of . What is the -coordinate?
This point has an x-coordinate of 8, so we can figure out what y is just by plugging in 8 for x:
This can be evaluated using a calculator, or just by understanding what a logarithm means.
This is essentially asking "2 to what power gives us 8," which is 3.
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