Solve the problem.
-Suppose that a sales person observes that if an item is priced at $7 per item then 11 items are sold. If 9 items are sold for $9 per item then find a linear function f(x) = mx + b whose input is the price
Of the item in dollars and whose output is the number of items sold.
A) f(x) = x + 18
B) f(x) = -x + 18
C) f(x) = -x + 4
D) f(x) = x + 4

Question

Quizplus · Accepted Answer

To find the linear function $f(x) = mx + b$, we use the given points (7, 11) and (9, 9), where x is the price and f(x) is the number of items sold. The slope $m$ is calculated as $\frac{9 - 11}{9 - 7} = \frac{-2}{2} = -1$. Using one of the points to solve for $b$, $11 = -1(7) + b$, we find $b = 18$. Thus, the function is $f(x) = -x + 18$.

Solve the Problem. -Suppose That a Sales Person Observes That If an Item