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.