Answer
a. $2$
b. The profit is increasing by $2$ thousand dollars per hundred units sold.
c. $-4.5$
Work Step by Step
$f(x)=2x-4.5=mx+c$
(a)
Where m is slope and c is y-intercept
$\Longrightarrow$
m=slope=2
(b)
Change=f(x+$\delta x$)-f(x)=2(x+$\delta x$)-4.5-(2x-4.5)
Change=2x+2$\delta x$-4.5-2x+4.5=2$\delta x$
$\Longrightarrow$
The profit is increasing by 2 thousand dollars per hundred units sold.
(c)
Putting x=0 in
$f(x)=2x-4.5$
$f(0)=2(0)-4.5=-4.5$
$x=0$ $\Longrightarrow$ No units are sold
When no units are sold the profit is -4.5 thousand
