All GMAT Math Resources
Example Questions
Example Question #4 : Coordinate Geometry
Define a function as follows:
Give the -intercept of the graph of .
The graph of has no -intercept.
The graph of has no -intercept.
The -coordinate of the -intercept is :
However, the logarithm of a negative number is an undefined expression, so is an undefined quantity, and the graph of has no -intercept.
Example Question #5 : Coordinate Geometry
Define a function as follows:
Give the equation of the vertical asymptote of the graph of .
Only positive numbers have logarithms, so
The graph never crosses the vertical line of the equation , so this is the vertical asymptote.
Example Question #6 : Coordinate Geometry
Define a function as follows:
Give the equation of the vertical asymptote of the graph of .
The graph of has no vertical asymptote.
Only positive numbers have logarithms, so
The graph never crosses the vertical line of the equation , so this is the vertical asymptote.
Example Question #7 : Coordinate Geometry
Define a function as follows:
Give the -intercept of the graph of .
The graph of has no -intercept.
The -coordinate of the -intercept is :
Since 2 is the cube root of 8, , and . Therefore,
.
The -intercept is .
Example Question #1 : Coordinate 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.
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 polynomial and the rational expression are equal, we can set those expressions themselves equal, then solve:
We can solve using the method, finding two integers whose sum is 24 and whose product is - these integers are 10 and 14, so we split the niddle term, group, and factor:
or
This gives us two possible -coordinates. However, since
,
an undefined quantity - negative numbers not having logarithms -
we throw this value out. As for the other -value, we evaluate:
and
is the correct -value, and is the correct -value.
Example Question #9 : Coordinate Geometry
Let be the point of intersection of the graphs of these two equations:
Evaluate .
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:
Now back-solve:
We need to find both and to ensure a solution exists. By substituting back:
.
is the solution, and , the correct choice.
Example Question #11 : Coordinate Geometry
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 #12 : Coordinate Geometry
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 #13 : Coordinate Geometry
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 #14 : 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 .