All GRE Subject Test: Math Resources
Example Questions
Example Question #1 : Circles
What is the equation of a circle with center at and a radius of ?
Step 1: Recall the general equation for a circle (if the vertex is not at :
, where center=
Step 2: Recall the shift of the graph..
If the value of is positive, it will be shown as a negative shift in the equation.
If the value of is negative, it will be shown as a positive shift in the equation.
If the value of is positive, it will be shown as a negative shift in the equation.
If the value of is negative, it will be shown as a positive shift in the equation.
Step 3: Look at the center given in the problem and find the rule(s) in step 2 that will apply:
Center=, ,
Step 4: Plug in into the equation of a circle:
Simplify:
Example Question #1 : Circles
What is the vertex of the equation of a circle:
Step 1: There are no numbers next to and , so their is no movement of the vertex..
Step 2: Recall the vertex of a circle that does not move...
The vertex of this circle is .
Example Question #2 : Conic Sections
Using the information below, determine the equation of the hyperbola.
Foci: and
Eccentricity:
General Information for Hyperbola:
Equation for horizontal transverse hyperbola:
Distance between foci =
Distance between vertices =
Eccentricity =
Center: (h, k)
First determine the value of c. Since we know the distance between the two foci is 12, we can set that equal to .
Next, use the eccentricity equation and the value of the eccentricity provided in the question to determine the value of a.
Eccentricity =
Determine the value of
Determine the center point to identify the values of h and k. Since the y coordinate of the foci are 4, the center point will be on the same line. Hence, .
Since center point is equal distance from both foci, and we know that the distance between the foci is 12, we can conclude that
Center point:
Thus, the equation of the hyperbola is:
Example Question #11 : Conic Sections
Using the information below, determine the equation of the hyperbola.
Foci: and
Eccentricity:
General Information for Hyperbola:
Equation for horizontal transverse hyperbola:
Distance between foci =
Distance between vertices =
Eccentricity =
Center: (h, k)
First determine the value of c. Since we know the distance between the two foci is 8, we can set that equal to .
Next, use the eccentricity equation and the value of the eccentricity provided in the question to determine the value of a.
Eccentricity =
Determine the value of
Determine the center point to identify the values of h and k. Since the y coordinate of the foci are 8, the center point will be on the same line. Hence, .
Since center point is equal distance from both foci, and we know that the distance between the foci is 8, we can conclude that
Center point:
Thus, the equation of the hyperbola is:
Example Question #2 : Solve A System Of Quadratic Equations
Find the coordinate of intersection, if possible: and .
To solve for x and y, set both equations equal to each other and solve for x.
Substitute into either parabola.
The coordinate of intersection is .
Example Question #3 : Solve A System Of Quadratic Equations
Find the intersection(s) of the two parabolas: ,
Set both parabolas equal to each other and solve for x.
Substitute both values of into either parabola and determine .
The coordinates of intersection are:
and
Example Question #1 : Solve A System Of Quadratic Equations
Find the points of intersection:
;
To solve, set both equations equal to each other:
To solve as a quadratic, combine like terms by adding/subtracting all three terms from the right side to the left side:
This simplifies to
Solving by factoring or the quadratic formula gives the solutions and .
Plugging each into either original equation gives us:
Our coordinate pairs are and .
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