All GMAT Math Resources
Example Questions
Example Question #1 : Graphing A Quadratic Function
What are the possible values of if the parabola of the quadratic function is concave upward and does not intersect the -axis?
The parabola cannot exist for any value of .
The parabola cannot exist for any value of .
If the graph of is concave upward, then .
If the graph does not intersect the -axis, then has no real solution, and the discriminant is negative:
For the parabola to have both characteristics, it must be true that and , but these two events are mutually exclusive. Therefore, the parabola cannot exist.
Example Question #2 : Graphing A Quadratic Function
Which of the following equations has as its graph a vertical parabola with line of symmetry ?
The graph of has as its line of symmetry the vertical line of the equation
Since in each choice, we want to find such that
so the correct choice is .
Example Question #3 : Graphing A Quadratic Function
Which of the following equations has as its graph a concave-right horizontal parabola?
None of the other responses gives a correct answer.
A horizontal parabola has as its equation, in standard form,
,
with real, nonzero.
Its orientation depends on the sign of . In the equation of a concave-right parabola, is positive, so the correct choice is .
Example Question #52 : Graphing
The graphs of the functions and have the same line of symmetry.
If we define , which of the following is a possible definition of ?
None of the other responses gives a correct answer.
The graph of a function of the form - a quadratic function - is a vertical parabola with line of symmetry .
The graph of the function therefore has line of symmetry
, or
We examine all four definitions of to find one with this line of symmetry.
:
, or
:
, or
, or
, or
Since the graph of the function has the same line of symmetry as that of the function , that is the correct choice.
Example Question #5 : Graphing A Quadratic Function
Give the -coordinate of a point at which the graphs of the equations
and
intersect.
We can set the two quadratic expressions equal to each other and solve for .
and , so
The -coordinates of the points of intersection are 2 and 6. To find the -coordinates, substitute in either equation:
One point of intersection is .
The other point of intersection is .
1 is not among the choices, but 41 is, so this is the correct response.
Example Question #6 : Graphing A Quadratic Function
Give the set of intercepts of the graph of the function .
The -intercepts, if any exist, can be found by setting :
The only -intercept is .
The -intercept can be found by substituting 0 for :
The -intercept is .
The correct set of intercepts is .
Example Question #7 : Graphing A Quadratic Function
Give the -coordinate of a point of intersection of the graphs of the functions
and
.
The system of equations can be rewritten as
.
We can set the two expressions in equal to each other and solve:
We can substitute back into the equation , and see that either or . The latter value is the correct choice.
Example Question #8 : Graphing A Quadratic Function
has as its graph a vertical parabola on the coordinate plane. You are given that and , but you are not given .
Which of the following can you determine without knowing the value of ?
I) Whether the graph is concave upward or concave downward
II) The location of the vertex
III) The location of the -intercept
IV) The locations of the -intercepts, if there are any
V) The equation of the line of symmetry
I and V only
I and III only
III and IV only
I, II, and V only
I, III, and IV only
I and III only
I) The orientation of the parabola is determined solely by the sign of . Since , the parabola can be determined to be concave downward.
II and V) The -coordinate of the vertex is ; since you are not given , you cannot find this. Also, since the line of symmetry has equation , for the same reason, you cannot find this either.
III) The -intercept is the point at which ; by substitution, it can be found to be at . known to be equal to 9, so the -intercept can be determined to be .
IV) The -intercept(s), if any, are the point(s) at which . This is solvable using the quadratic formula
Since all three of and must be known for this to be evaluated, and only is known, the -intercept(s) cannot be identified.
The correct response is I and III only.
Example Question #161 : Coordinate Geometry
Which of the following equations can be graphed with a vertical parabola with exactly one -intercept?
The graph of has exactly one -intercept if and only if
has exactly one solution - or equivalently, if and only if
Since in all three equations, , we find the value of that makes this statement true by substituting and solving:
The correct choice is .
Example Question #162 : Coordinate Geometry
Give the vertex of the graph of the function
.
This can be answered rewriting this expression in the form
.
Once this is done, we can identify the vertex as the point .
The vertex is