When a table of data is given without a verbal description of the relationship, it is helpful to find the relationship between the data.

Example:

Fill in the blanks.

Looking at the table, a pattern is visible.

• For each pound of crawfish, the price is Interactive button. Assistance may be required. _____ $3.
• To find the cost of 10 pounds of crawfish, Interactive button. Assistance may be required. _____ multiply 10 × $3 to get $30.
• The algebraic equation is Interactive button. Assistance may be required. _____ y = 3x.

Not all tables have a visible pattern, at times the pattern is more difficult to see.

When this happens, the rate of change can be calculated and used to find the relationship between the values. This relationship can be expressed as the equation.

Example:

In this table the rate of change is $0.50 for each minute. There is also $2 added to each call. So to predict the cost for a 10 minute call, multiply 0.50(10) + 2 to get $7. y = 0.50x + 2 on writing an equation in slope-intercept form.