# HiSET: Math : Write a function that describes a relationship between two quantities

## Example Questions

### Example Question #1 : Write A Function That Describes A Relationship Between Two Quantities

is a linear function defined on the set of real numbers. Four values of are given in the following table:

Give the definition for .

Explanation:

By the two-point formula, the equation of a line through points is

,

where , the slope of the line. The choice of the two points from the given four is arbitrary, so we will select the middle two ordered pairs. Substituting , then

The first formula becomes

Since , solve for . First, distribute throughout the difference at right:

Isolate by adding 10 to both sides:

Replacing, the definition of is

.