All Precalculus Resources
Example Questions
Example Question #1793 : Pre Calculus
Find the foci for the hyperbola with the following equation:
Recall that the standard formula of a hyperbola can come in two forms:
and
, where the centers of both hyperbolas are .
When the term with is first, that means the foci will lie on a horizontal transverse axis.
When the term with is first, that means the foci will lie on a vertical transverse axis.
To find the foci, we use the following:
For a hyperbola with a horizontal transverse access, the foci will be located at and .
For a hyperbola with a vertical transverse access, the foci will be located at and .
For the given hypebola in the question, the transverse axis is vertical and its center is located at .
Next, find .
The foci are then located at and .
Example Question #1794 : Pre Calculus
Which point is one of the foci of the hyperbola ?
To find the foci of a hyperbola, first determine a and b, and then use the relationship
In this case, the major axis is horizontal since x comes first, so and .
Solve for c: add 9 to both sides
take the square root
Since the center is and the major axis is the horizontal one, our foci are . The only choice that works is
.
Example Question #121 : Understand Features Of Hyperbolas And Ellipses
Determine the length of the foci for the following hyperbola equation:
To solve, simply use the follow equation where c is the length of the foci.
In this particular case,
Thus,
Example Question #1795 : Pre Calculus
Find the foci of the hyperbola with the following equation:
and
and
and
and
and
and
The standard form of the equation for a hyperbola is given by
The foci are located at (h+c, k) and (h-c, k), where c is found by using the formula
Since our equation is already in standard form, you can see that
,
Plugging into the formula
So the foci are found at
AND
Example Question #1791 : Pre Calculus
How can this graph be changed to be the graph of
?
The -intercepts should be at the points and .
The center box should extend up to and down to , stretching the graph.
The graph should have -intercepts and not -intercepts.
The graph should be an ellipse and not a hyperbola.
The -intercepts should be at the points and .
The -intercepts should be at the points and .
This equation should be thought of as .
This means that the hyperbola will be determined by a box with x-intercepts at and y-intercepts at .
The hyperbola was incorrectly drawn with the intercepts at instead.
Example Question #211 : Conic Sections
Which of the following would NOT be true of the graph for ?
The graph opens up and down.
The graph is centered at .
The graph never intersects with the -axis.
All of these statements are true.
The graph never intersects with the -axis.
The graph never intersects with the -axis.
The graph should look like this:
Example Question #1797 : Pre Calculus
Which of these equations produce this graph, rotated 90 degrees?
Rotated 90 degrees, this graph would be opening up and down instead of left and right, so the equation will have the y term minus the x term.
The box that the hyperbola is drawn around will also rotate. It will now be up/down 2 and left/right 3.
This makes the correct equation
.
Example Question #125 : Hyperbolas And Ellipses
What is the equation of the conic section graphed below?
The hyperbola pictured is centered at , meaning that the equation has a horizontal shift. The equation must have rather than just x. The hyperbola opens up and down, so the equation must be the y term minus the x term. The hyperbola is drawn according to the box going up/down 5 and left/right 2, so the y term must be or , and the x term must be or .
Example Question #1801 : Pre Calculus
The equation of an ellipse, , is . Which of the following is the correct eccentricity of this ellipse?
The equation for the eccentricity of an ellipse is , where is eccentricity, is the distance from the foci to the center, and is the square root of the larger of our two denominators.
Our denominators are and , so .
To find , we must use the equation , where is the square root of the smaller of our two denominators.
This gives us , so .
Therefore, we can see that
.
Example Question #1 : Determine The Equation Of A Parabola And Graph A Parabola
Determine the direction in which the following parabola opens, if the y-axis is vertical and the x-axis is horizontal:
Left
Right
Up
Down
Along
Left
In order to determine which direction the parabola opens, we must first put the equation in standard form, which can be expressed in one of the following two ways:
If the equation is for as in the first above, the parabola opens up if is positive and down if is negative. If the equation is for as in the second above, the parabola opens right if is positive and left if is negative. Rearranging our equation, we get:
We can see that our equation is for , which means the parabola will open either left or right. The sign of the first term is negative, so this parabola will open to the left.
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