Sure! Let's break down the linear function \( m = 50 - 9d \) step by step.
a. Interpret the terms and coefficient in the equation
- m: This represents the amount of money (in dollars) you have left after purchasing DVDs.
- d: This is the number of DVDs you have bought.
- 50: This is the initial amount of money you have (in dollars) before purchasing any DVDs.
- -9: This is the coefficient of \( d \), representing the cost of each DVD. Specifically, it indicates that each DVD costs $9. As you buy more DVDs (increase \( d \)), your remaining money decreases by $9 for each additional DVD purchased.
b. Find the domain of the function. Is the domain discrete or continuous?
The domain of the function represents the valid values of \( d \) (the number of DVDs bought). In this context:
- \( d \) cannot be negative because you cannot buy a negative number of DVDs.
- The maximum number of DVDs you can buy occurs when \( m \) reaches zero (i.e., you spend all your money). To find the maximum \( d \), we can set \( m = 0 \) and solve for \( d \):
\[ 0 = 50 - 9d \ 9d = 50 \ d = \frac{50}{9} \approx 5.56 \]
Since you cannot buy a fraction of a DVD, the maximum whole number of DVDs you can buy is 5.
Thus, the domain of \( d \) in the context of this equation is:
\[ d \in {0, 1, 2, 3, 4, 5} \]
This shows that the values of \( d \) can only take on whole numbers from 0 to 5.
Is the domain discrete or continuous?
The domain is discrete because \( d \) can only take integer values (whole numbers) rather than every possible real number in the interval.