All GMAT Math Resources
Example Questions
Example Question #71 : 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 #72 : Graphing
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 #13 : Coordinate Geometry
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 #14 : Coordinate Geometry
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 #101 : Advanced Geometry
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 #16 : Coordinate Geometry
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 #84 : Graphing
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 : Graphing
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 #1 : How To Graph Complex Numbers
Give the -intercept(s) of the parabola with equation . Round to the nearest tenth, if applicable.
The parabola has no -intercept.
The parabola has no -intercept.
The -coordinate(s) of the -intercept(s) are the real solution(s) to the equation . We can use the quadratic formula to find any solutions, setting - the coefficients of the expression.
An examination of the discriminant , however, proves this unnecessary.
The discriminant being negative, there are no real solutions, so the parabola has no -intercepts.
Example Question #1 : How To Graph Complex Numbers
In which quadrant does the complex number lie?
-axis
When plotting a complex number, we use a set of real-imaginary axes in which the x-axis is represented by the real component of the complex number, and the y-axis is represented by the imaginary component of the complex number. The real component is and the imaginary component is , so this is the equivalent of plotting the point on a set of Cartesian axes. Plotting the complex number on a set of real-imaginary axes, we move to the left in the x-direction and up in the y-direction, which puts us in the second quadrant, or in terms of Roman numerals: