I REALLY NEED HELP!

Question

Consider the following "table" of functional values: (-1,-1.32), (-0.2,-6.6), (1.1,1.2), (2.2,0.6). Does the function vary directly, vary inversely, or neither? If it varies, what is the constant of variation?
 

Varies directly; k = 1.32

Neither, since xy is not a constant

Neither, since y/x is not a constant

Varies inversely; k = 13.2

Varies inversely; k = 1.32
 

Consider the following "table" of functional values: (-1.5,-6), (1,4), (2.1,8.4), (3.6,14.4). Does the function vary directly, vary inversely, or neither? If it varies, what is the constant of variation?
 

Varies inversely: k = 4

Varies directly: k = 1/4

Varies inversely: k = 1/4

Neither

Varies directly: k = 4
 

The variables x and y vary inversely. Write the function that models this inverse variation if x = 7 when y = 42.
 

y = 6 / x

y = 294 / x

y = 6x

x = 294y

y = 294x

Answer 1

Mark M is right. 

An inverse relation is like y=k/x 

In this case k=xy (multiply the x and y of each point and they are the same for all points).

For the first problem, you should calculate

-1 x -1.32 = ?

-0.2 x -6.6 = ? 

etc. and see if they are all the same. If they are it is an inverse relation.

 

A direct relation is like y=kx. In this case when you DIVIDE y by x for each point they are the same (=k). 

 

y= -5x is not an inverse relation, because when you divide y by x, you always get -5. It is not inverse, though you can find people saying so (e.g. Yahoo Answers).