Michelle rents a movie for a flat fee of $1.50 plus an additional $1.25 for each night she keeps the movie. Choose the cost function that represents this scenario if x equals the number of nights Michelle has the movie.

c(x) = 1.50 + 1.25x

c(x) = 1.50x + 1.25

c(x) = 2.75

c(x) = (1.50 + 1.25)x

Question

Michelle rents a movie for a flat fee of $1.50 plus an additional $1.25 for each night she keeps the movie. Choose the cost function that represents this scenario if x equals the number of nights Michelle has the movie.

 c(x) = 1.50 + 1.25x

 c(x) = 1.50x + 1.25

 c(x) = 2.75

 c(x) = (1.50 + 1.25)x

anonymous · Answer

Okay. Well no matter what she'll be paying $1.50 since that's the flat fee. So it's $1.50 plus how much she's paying for whatever time she keeps it. If I'm paying 2 dollars a night and I'm keeping the movie for 3 nights, I would multiply 2 and 3 to find out I'm paying $6. 

So if x is the amount of days she is keeping the movie, you're going to multiply that by the cost per night-$1.25.
So the answer is c(x)= 1.50 + 1.25x, your first choice.

Do you understand?

anonymous · Answer

yes! thanks so much!!!!!

anonymous · Answer

You're welcome. :)

anonymous · Answer

hey! @JakeV8

anonymous · Answer

Let's try this one...

Laura rents a movie for a flat fee of $2.00 plus an additional $0.50 for each night she keeps the movie. If Laura returned the movie and paid $5.00, how many nights did she keep the movie?

anonymous · Answer

Do you understand the idea of the cost function?  If not, we can back up one step.

anonymous · Answer

# nights   flat fee  0.50 per-night cost     total cost
-------   ------  -----------------    --------
     0           $2        0                                   $2
     1           $2         0.50 * 1 = 0.50            $2.50
     2            $2       0.50 * 2 = 1.00              $3.00
     3             $2     0.50 * 3 = 1.50               $3.50

in general:
 x nights      $2          0.50 * x                  c(x) = 2 + 0.50x