Question

Lexi has $80 to spend on an ice cream treat each week. If she spends $4 on ice cream per week, the function C(x)=80−4x

Answer 1

Answer:

Domain$=\{1,2,3,4,5,6,7,8,9,10,11,12,,13,14,15,16,17,18,19,20\}$

In other words Domain$=\{x|x\ is\ an\ integer\ and\ 1\leq x\leq20\}$

Step-by-step explanation:

$C(x)=80-4x$

Let after $t$ weeks she has left no money.

$c(t)=0\\80-4t=0\\4t=80\\t=20$

That means she can have money for ice cream from the week 1 to week 20 and after that she will have no money.

So $x$ can be any number between $1$ and $20$

Hence Domain$=\{x|x\ is\ an\ integer\ and\ 1\leq x\leq20\}$