Advanced Geometry : Coordinate Geometry

Study concepts, example questions & explanations for Advanced Geometry

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Example Questions

Example Question #51 : Coordinate Geometry

Give the -coordinate of the -intercept of the graph of the function 

Possible Answers:

Correct answer:

Explanation:

The -intercept(s) of the graph of  are the point(s) at which it intersects the -axis. The -coordinate of each is 0,; their -coordinate(s) are those value(s) of  for which , so set up, and solve for , the equation:

Add 8 to both sides:

Divide both sides by 2:

Take the common logarithm of both sides to eliminate the base:

Example Question #52 : Coordinate Geometry

Give the domain of the function .

Possible Answers:

The set of all real numbers

Correct answer:

The set of all real numbers

Explanation:

Let . This function is defined for any real number , so the domain of  is the set of all real numbers. In terms of ,

Since  is defined for all real , so is ; it follows that  is as well. The correct domain is the set of all real numbers.

Example Question #51 : Graphing

Give the range of the function .

Possible Answers:

The set of all real numbers

Correct answer:

Explanation:

Since a positive number raised to any power is equal to a positive number, 

Applying the properties of inequality, we see that

,

and the range of  is the set .

Example Question #51 : Graphing

What are the possible values of  if the parabola of the quadratic function   is concave upward and does not intersect the -axis?

Possible Answers:

The parabola cannot exist for any value of .

Correct answer:

The parabola cannot exist for any value of .

Explanation:

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 #991 : Gmat Quantitative Reasoning

Which of the following equations has as its graph a vertical parabola with line of symmetry  ?

Possible Answers:

Correct answer:

Explanation:

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 #52 : Graphing

Which of the following equations has as its graph a concave-right horizontal parabola?

Possible Answers:

None of the other responses gives a correct answer.

Correct answer:

Explanation:

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 #53 : 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  ?

Possible Answers:

None of the other responses gives a correct answer.

Correct answer:

Explanation:

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 #51 : Coordinate Geometry

Give the -coordinate of a point at which the graphs of the equations 

and 

intersect.

Possible Answers:

Correct answer:

Explanation:

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 #995 : Gmat Quantitative Reasoning

Give the set of intercepts of the graph of the function .

Possible Answers:

Correct answer:

Explanation:

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 #996 : Gmat Quantitative Reasoning

Give the -coordinate of a point of intersection of the graphs of the functions

and 

.

Possible Answers:

Correct answer:

Explanation:

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.

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