Interpret rate of change

Question

A cell phone company charges a monthly rate according to the formula C(n) = 40 + 10n. Find and interpret the rate of change and initial value for this function. Write in complete sentences

Answer 1

Hi Chance,

 

One way to look at the question is through linear equation :

 

C(n) = 40 +10 n shows that 10 is the slope of the equation and gives the rate of change. 

The initial value is given when n = 0.

 

So, the rate of change of the function is 10 per unit , implying that for every unit increase (or change) in n  the charges increase (or change) by 10 units.

 

The initial value of the function is 40 and the charges cannot go below 40 (assuming n cannot take values below 0).