Direct and Inverse Variation

One nice little topic you will study as an algebra student is variation.  The concept takes a look at how variables relate to one another in equations and especially in formulas.  There are a few different types of variation you need to know but I want to focus on direct and inverse variation. Let’s explore direct variation first by looking at the formula T=PV or Temperature = Pressure * Volume.   To demonstrate this formula think about a pot filled with water on your stove- the pot also has a cover.  Now if you turn up the fire on your stove the temperature goes up- what will happen to the pressure inside the pot?  Clearly as the temperature goes up the pressure inside the pot goes up- this type of relationship between the variables T and P is an example of direct variation.  Now lets look at and inverse example.  Lets consider the fact that the interest rate on a loan is related to a person’s credit score.  More specifically if a person’s credit score goes down their loan interest rate goes up- and the opposite is true as their credit score goes up their loan rate will go down.  This loan and credit score relationship is an example of inverse variation.  The notes below explain the steps to work direct and inverse variation problems.  Pay attention to the notes as it will help you in algebra and possibly help you save money on a loan…



some key topics that involve direct and inverse variation:

* ratios and proportions
* linear equations and formulas
* joint variation
* physics

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