what does varies indirectly mean in math?

Question

I just need to know and these websites wont tell

Answer 1

Hi Ta,

 

Strictly speaking, two objects or variables "vary indirectly" means that the product of the two items is a constant. For example, x and y vary indirectly means x*y is constant.

 

Saying "one variable goes up as the other goes down" is incomplete. While it is true that all indirect variation relations have this up/down property, we can imagine many functions, such as y = -x, that also have the property that as one variable goes up, the other goes down. However, y = -x is not inverse variation, it is direct variation !

 

Thus, it is best to think of inverse variation as "product is constant". That will always say that as one goes up, the other goes down. The converse is not true -- saying as one goes up, the other goes down does not always mean product is constant, as our example y = -x shows.

 

I hope this helps.

Answer 2

There are two types of variation used in math.

 

Direct variation means  (Y varies directly with x)  y = kx

 

Indirect variation means (Y varies indirectly with x ) y = k/x

 

So, if the question says -  y varies indirectly with x, and for a value of x=3, y=4, then this is the problem to solve.

 

            y = k/x

            4 = k/3

            k = 3x4 = 12

Therefore, the equation is then y = 12/x

 

Hope this helps.

Bill.

 

 

Answer 3

When y varies directly with x, any increase in x will result in an increase in y. Examples are y=3x+7. 

 

The converse is y varies inversely with x such as y=10/x where any increase in x results in a decrease in y.

 

Hope this clears it up.

 

Jim

Answer 4

At its most simple, inverse variation means as one variable goes up, the other goes down. Direct means as one goes up, the other goes up.

 

Mathematically, the relationship follows the equations Bill provided.