All GMAT Math Resources
Example Questions
Example Question #31 : Coordinate Geometry
Graph the point .
I) is in quadrant IV.
II) .
Statement I is sufficient to answer the question, but statement II is not sufficient to answer the question.
Both statements are needed to answer the question.
Either statement is sufficient to answer the question.
Statement II is sufficient to answer the question, but statement I is not sufficient to answer the question.
Neither statement is sufficient to answer the question. More information is needed.
Both statements are needed to answer the question.
Graph the point (a,b)
I) (a,b) is in quadrant 4
II)
To graph (a,b) we need to know a and b
I) Tells us which quadrant the point is in. In quadrant 4, the x value is positive and the y value must be negative.
II) Lets us find the following:
So the only possible location of is .
Therefore, both statements are needed to answer the question.
Example Question #32 : Coordinate Geometry
Graph the exponential function .
I) is a monomial.
II) has a base of 4.
Either statement is sufficient to answer the question.
Both statements are needed to answer the question.
Neither statement is sufficient to answer the question. More information is needed.
Statement II is sufficient to answer the question, but Statement I is not sufficient to answer the question.
Statement I is sufficient to answer the question, but Statement II is not sufficient to answer the question.
Neither statement is sufficient to answer the question. More information is needed.
An exponential function follows the general form of
Statement I tells us that there is only one term, so the part of the equation isn't needed for this exponential function.
Statement II tells us that in this case, .
However, we could have nearly anything as our exponent. We are unable to make an accurate graph of this function, so more information is needed.
Example Question #31 : Graphing
The graph of the function is a parabola. Is this parabola concave upward or is it concave downward?
Statement 1:
Statement 2:
BOTH statements TOGETHER are sufficient to answer the question, but NEITHER statement ALONE is sufficient to answer the question.
BOTH statements TOGETHER are insufficient to answer the question.
EITHER statement ALONE is sufficient to answer the question.
Statement 1 ALONE is sufficient to answer the question, but Statement 2 ALONE is NOT sufficient to answer the question.
Statement 2 ALONE is sufficient to answer the question, but Statement 1 ALONE is NOT sufficient to answer the question.
Statement 1 ALONE is sufficient to answer the question, but Statement 2 ALONE is NOT sufficient to answer the question.
Whether the parabola of a quadratic function is concave upward or concave downward depends on one thing and one thing only - whether quadratic coefficient is positive or negative. Statement 1 gives you this information; Statement 2 does not.
Example Question #33 : Coordinate Geometry
What is the equation of the line of symmetry of a vertical parabola on the coordinate plane?
Statement 1: The -intercept of the parabola is .
Statement 2: The only -intercept of the parabola is at .
BOTH statements TOGETHER are insufficient to answer the question.
BOTH statements TOGETHER are sufficient to answer the question, but NEITHER statement ALONE is sufficient to answer the question.
Statement 2 ALONE is sufficient to answer the question, but Statement 1 ALONE is NOT sufficient to answer the question.
EITHER statement ALONE is sufficient to answer the question.
Statement 1 ALONE is sufficient to answer the question, but Statement 2 ALONE is NOT sufficient to answer the question.
Statement 2 ALONE is sufficient to answer the question, but Statement 1 ALONE is NOT sufficient to answer the question.
The line of symmetry of a vertical parabola is the vertical line passing through the vertex. Statement 1 alone is not helpful, since it only gives the -intercept.
Statement 2 alone, however, answers the question. In a parabola with only one -intercept, that -intercept, given in Statement 2 as , doubles as the vertex. The vertical line through the vertex, which here is the line with equation , is the line of symmetry.
Example Question #32 : Graphing
The equation of a vertical parabola on the coordinate plane can be written in the form
, real, nonzero.
How many -intercepts does the parabola have - zero, one, or two?
Statement 1:
Statement 2:
EITHER statement ALONE is sufficient to answer the question.
Statement 1 ALONE is sufficient to answer the question, but Statement 2 ALONE is NOT sufficient to answer the question.
BOTH statements TOGETHER are sufficient to answer the question, but NEITHER statement ALONE is sufficient to answer the question.
Statement 2 ALONE is sufficient to answer the question, but Statement 1 ALONE is NOT sufficient to answer the question.
BOTH statements TOGETHER are insufficient to answer the question.
Statement 1 ALONE is sufficient to answer the question, but Statement 2 ALONE is NOT sufficient to answer the question.
Assume Statement 1 alone. The number of -intercepts of the graph of the function - depends on the sign of the discriminant of the expression, .
If , then the discriminant becomes
Since in a quadratic equation, is nonzero, must be positive, and discriminant must be negative. This means that the parabola of has no -intercepts.
We show that Statement 2 alone gives insufficient information by examining two equations: and . In both equations, the sum of the coefficients is 9.
In the first equation, the discriminant is
, a positive value, so the parabola of has two -intercepts.
In the second equation, however, the discriminant is
, a negative value, so the parabola of has no -intercepts.
Example Question #4 : Dsq: Graphing A Quadratic Function
What is the equation of the line of symmetry of a vertical parabola on the coordinate plane?
Statement 1: The parabola passes through points and .
Statement 2: The parabola passes through the points and .
EITHER statement ALONE is sufficient to answer the question.
BOTH statements TOGETHER are sufficient to answer the question, but NEITHER statement ALONE is sufficient to answer the question.
Statement 1 ALONE is sufficient to answer the question, but Statement 2 ALONE is NOT sufficient to answer the question.
Statement 2 ALONE is sufficient to answer the question, but Statement 1 ALONE is NOT sufficient to answer the question.
BOTH statements TOGETHER are insufficient to answer the question.
EITHER statement ALONE is sufficient to answer the question.
Assume Statement 1 alone. By vertical symmetry, if two points of a parabola have the same -coordinate, the line of symmetry is the vertical line that passes halfway between them. and have the same -coordinate, so the axis of symmetry must be
, or .
Statement 1 alone is sufficient.
Statement 2 can be proved sufficient using a similar argument.
Example Question #5 : Dsq: Graphing A Quadratic Function
What is the equation of the line of symmetry of a horizontal parabola on the coordinate plane?
Statement 1: The vertex of the parabola has -coordinate 4.
Statement 2: The vertex of the parabola has -coordinate 9.
Statement 2 ALONE is sufficient to answer the question, but Statement 1 ALONE is NOT sufficient to answer the question.
EITHER statement ALONE is sufficient to answer the question.
Statement 1 ALONE is sufficient to answer the question, but Statement 2 ALONE is NOT sufficient to answer the question.
BOTH statements TOGETHER are insufficient to answer the question.
BOTH statements TOGETHER are sufficient to answer the question, but NEITHER statement ALONE is sufficient to answer the question.
Statement 2 ALONE is sufficient to answer the question, but Statement 1 ALONE is NOT sufficient to answer the question.
The line of symmetry of a horizontal parabola with vertex at is the horizonal line of the equation . In other words, the -coordinate of the vertex, which is given in Statement 2 but not Statement 1, is the one and only thing needed.
Example Question #6 : Dsq: Graphing A Quadratic Function
The equation of a vertical parabola on the coordinate plane can be written in the form
, real, nonzero.
Is this parabola concave upward or concave downward?
Statement 1: .
Statement 2: The parabola has -intercept .
Statement 2 ALONE is sufficient to answer the question, but Statement 1 ALONE is NOT sufficient to answer the question.
BOTH statements TOGETHER are sufficient to answer the question, but NEITHER statement ALONE is sufficient to answer the question.
Statement 1 ALONE is sufficient to answer the question, but Statement 2 ALONE is NOT sufficient to answer the question.
BOTH statements TOGETHER are insufficient to answer the question.
EITHER statement ALONE is sufficient to answer the question.
BOTH statements TOGETHER are sufficient to answer the question, but NEITHER statement ALONE is sufficient to answer the question.
Assume Statement 1 alone. Since - that is, the function has a negative discriminant - the graph of has no -intercepts. This alone, however, does not determine whether the parabola is concave upward or concave downward. Also, Statement 2 alone only gives one point of the parabola, thereby providing insufficient information.
Now assume both statements are true. From Statement 2, , so the parabola has a point above the -axis. If the parabola is concave downward, then it must cross the -axis, which is impossible as a result of Statement 1. The parabola therefore must be concave upward.
Example Question #32 : Coordinate Geometry
The equation of a vertical parabola on the coordinate plane can be written in the form
,
where are real, and is a nonzero number.
How many -intercepts does this parabola on the coordinate plane have - zero, one, or two?
Statement 1:
Statement 2:
BOTH statements TOGETHER are insufficient to answer the question.
EITHER statement ALONE is sufficient to answer the question.
Statement 2 ALONE is sufficient to answer the question, but Statement 1 ALONE is NOT sufficient to answer the question.
BOTH statements TOGETHER are sufficient to answer the question, but NEITHER statement ALONE is sufficient to answer the question.
Statement 1 ALONE is sufficient to answer the question, but Statement 2 ALONE is NOT sufficient to answer the question.
Statement 1 ALONE is sufficient to answer the question, but Statement 2 ALONE is NOT sufficient to answer the question.
Assume Statement 1 alone. The number of -intercepts(s) of the graph of depends on the sign of discriminant . By Statement 1, , or, equivalently, , which means that the parabola of has exactly one -intercept.
Statement 2 alone, that the quadratic coefficient is positive, only establishes that the parabola is concave upward. Therefore, it gives insufficient information.
Example Question #8 : Dsq: Graphing A Quadratic Function
How many -intercepts does a vertical parabola on the coordinate plane have - zero, one, or two?
Statement 1: The vertex of the parabola is .
Statement 2: The -intercept of the parabola is .
Statement 1 ALONE is sufficient to answer the question, but Statement 2 ALONE is NOT sufficient to answer the question.
BOTH statements TOGETHER are sufficient to answer the question, but NEITHER statement ALONE is sufficient to answer the question.
Statement 2 ALONE is sufficient to answer the question, but Statement 1 ALONE is NOT sufficient to answer the question.
EITHER statement ALONE is sufficient to answer the question.
BOTH statements TOGETHER are insufficient to answer the question.
BOTH statements TOGETHER are sufficient to answer the question, but NEITHER statement ALONE is sufficient to answer the question.
From Statement 1, since the vertex is not on the -axis - its -coordinate is nonzero - the parabola has either zero or two -intercepts. However, with no further information, it is not possible to choose. Statement 2 alone is not helpful since it only gives one point, and no further information about it.
Assume both statements to be true. We can find the equation of the parabola as follows:
A parabola with vertex has equation
for some nonzero .
From Statement 1, , so the equation becomes
Since the parabola passes through To find , we substitute 0 for and 21 for :
The equation of the parabola is .
Now that the equation is known, the -intercept(s) themselves, if any, can be found by substituting 0 for .