Steply

Which conic is 4x^2 - y^2 - 16 = 0

Step by step, with the reason for every step · Conics from the general form · Precalculus

Step by step

The question

Question: name the conic and write in standard form 4x² − y² − 16 = 0.

4x2 − y2 − 16 = 0

1 Name the conic

Look at the squares.

x² and y² have different signs.

So it is a hyperbola.

only x² or only y² → parabola
x² and y², same number in front → circle
same signs, different numbers → ellipse
different signs → hyperbola ✓

2 Move the number

Move the plain number to the right: − 16 becomes + 16.

4x2 − y2 = 16

3 Make the right side 1

Divide every part by 16, so the right side is 1.

4/16 is 1/4.

x24 − y216 = 1
16 ÷ 4 = 4, 16 ÷ −1 = -16

That is the standard form of a hyperbola with center (0, 0).

hyperbola: center (0, 0)

4 Check

Let's check with a point on it: (2, 0), a vertex.

Put it in the first equation.

4 × 2² − 0² − 16 = 16 + 0 − 16 = 0

We get 0, like the first equation says.

So the standard form is right!

Let's look back.

First: name the conic.

Then: move the number.

Then: make the right side 1.

Last: check.

Answer
16 ÷ 4 = 4, 16 ÷ −1 = -16

Your turn

Try this one yourself, then check:

Name the conic and write in standard form 4x2 − y2 − 4 = 0
Show the answer
x2 − y24 = 1

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