To sketch a hyperbola:
x squared over A squared minus y squared over b squared equals 1
If the x squared term is positive, the hyperbola is horizontal.
x-intercepts: (negative A comma 0) and (A,0) and no y-intercepts.
⇨
y squared over b squared minus x squared over A squared equals 1
If the y squared term is positive, the hyperbola is vertical.
y-intercepts: (0, negative b) and (0, b) and no x-intercepts.
⇨
Symetric about both the x and y axes
Center: (0,0)
Asymptotes: y equals plus minus b over A times x
Graph: x squared over 16 minus y squared over 9 equals 1
The x squared term is positive, so the hyperbola is horizontal; in other words, its branches open to the left and to the right.
To get the x-intercepts:
x squared over 16 minus 0 squared over 9 equals 1rightward arrow x squared over 16 equals 1rightward arrow x squared equals 16rightward arrow x equals plus minus 4
Therefore the x-intercepts are ( negative 4,0) and (4,0).
The x-intercepts are given by the positive and negative squarede roots of the denominator of the x squared term.
There are no y-intercepts.
A squared equals 16 and b squared equals 9, so A = 4 and b = 3.
The asymptotes, which are given by y equals plus minus b over A times x, are y equals plus minus three fourths times x.
Graph: y squared over 25 minus x squared over 9 equals 1
The y squared term is positive, so the hyperbola is vertical; in other words, its branches open upward and downward.
To get the y-intercepts:
y squared over 25 minus 0 squared over 9 equals 1 rightward arrow y squared over 25 equals 1 rightward arrow y squared equals 25 rightward arrow y equals plus minus 5
Therefore the y-intercepts are (0,-5) and (0,5).
The y-intercepts are given by the positive and negative square roots of the denominator of the y squared term.
There are no x-intercepts.
A squared equals 9 and b squared equals 25, so A = 3 and b = 5
The asymptotes, which are given by y equals plus minus b over A times x, are y equals plus minus five thirds times x.
In the following exploration you will select values for A and B and then see the corresponding graph of x squared over A squared minus y squared over b squared equals 1
You will find that all the hyperbolas generated in this exploration are horizontal because the x squared term is positive.
You will see how A squared, the denominator of the x squared, determines the x-intercepts and that there are no y-intercepts.
Finally, you will note that the asymptotes are lines that go through the origin with slopes of b over A and negative b over A.
Graph: x squared over A squared minus y squared over b squared equals 1
Click on the boxes and select values for a and b. Then click on "Plot" to see the hyperbola that results. When you have finished your exploration, click on the Next button to continue.
a
b
x squared over A squared minus y squared over b squared equals 1
In the following exploration you will select values for A and B and then see the corresponding graph of y squared over b squared minus x squared over A squared equals 1
You will find that all the hyperbolas generated in this exploration are vertical because the y squared term is positive.
You will see how b squared, the denominator of the y squared term, determines the y-intercepts and that there are no x-intercepts.
Finally, you will note that the asymptotes are lines that go through the origin with slopes of b over A and negative b over A
Graph: y squared over b squared minus x squared over A squared equals 1
Click on the boxes and select values for a and b. Then click on "Plot" to see the hyperbola that results. When you have finished your exploration, click on the Next button to continue.
a
b
y squared over b squared minus x squared over A squared equals 1
The Graph of x squared over A squared minus y squared over b squared equals 1 or y squared over b squared minus x squared over A squared equals 1, where A is larger than 0 and b is larger than 0:
Is horizontal if x squared term is positve
Is vertical if y squared term is positve
Has y equals plus minus b over A times x as asymptotes
Once you are comfortable graphing hyperbolas centered at the origin, you will find it easy to graph hyperbolas centered at points other than the origin.