What is an inverse variation?

Inverse variation is a relationship between two variables. It shows that when one variable increases, the other variable decreases.

Expert Answers

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Inverse variation is also known as inverse proportion. From the word "inverse", when the value of the variable increases, the other variable decreases. This relationship is described by the equation

`y= k/x`

where k is the proportionality constant, x and y are the variables.

Take note that k is any real number except zero. Also, the values of x and y can not also be zero.

Consider the following example:

It is given that a varies inversely with b. When a = 2, the value of b is 3.

(a) What is the equation of inverse variation that relates b to a?

(b) Do the values of b increases when the values of a changes from 1 to 0.5?


(a) Apply the equation `y=k/x` . To do so, replace the variable x and y with a and b, respectively.

`b = k/a`

Plug in the given values of a and b.

`3 = k/2`

Then, solve for the proportionality constant, k.

`3*2 = k`


And, plug-in the value of k.


Therefore, the equation of this inverse variation is `b = 6/a.`

(b) To determine the values of b for each given value of a, plug in the values of a to the equation above.

`a = 1, b=6/1=6`

`a = 0.5, b=6/0.5 = 12`

So, the corresponding values of b are as follows:

a b

1 6

0.5 12

Therefore, this verifies that as the values of a decreases, b increases.

Last Updated by eNotes Editorial on September 14, 2020
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