Question 375122
First off, "indirect " variation and "inverse" variation mean exactly the same thing.
What is it.
When one quantity decreases as another quantity increases, the two quantities are said to vary inversely or indirectly.
Here's an example:
The air temperature goes down the higher you go.
So as the height increases, the temperature decreases. 
We say that the air temperature varies inversely (indirectly) as the height.
You can write this algebraically as: (h = height and T = temperature)
{{{T = k/h}}} The k is called the constant of variation and its value will depend upon the initial values of h and T that are provided in the problem.
For example, if you are told that the air temperature is 30 degrees farenheit at a height of 10,000 feet, you have enough information to find the value of k, the constant of variation.
{{{T = k/h}}} Substitute T = 30 and h = 10,000
{{{30 = k/10000}}} Multiply both sides by 10,000
{{{k = 300000}}} so the equation now is:
{{{T = 300000/h}}} and this allows you to find the air temperature at any height, h.