Question

Matt sells burgers and sandwiches. The daily cost of making burgers is $520 more than the difference between the square of the number of burgers sold and 30 times the number of burgers sold. The daily cost of making sandwiches is modeled by the following equation:

C(x) = 2x2 - 40x + 300

C(x) is the cost in dollars of selling x sandwiches.

Answer 1

@phi

Answer 2

Which statement best compares the minimum daily cost of making burgers and sandwiches?

It is greater for sandwiches than burgers because the approximate minimum cost is $250 for burgers and $292 for sandwiches.
It is greater for sandwiches than burgers because the approximate minimum cost is $100 for burgers and $295 for sandwiches.
It is greater for burgers than sandwiches because the approximate minimum cost is $295 for burgers and $100 for sandwiches.
It is greater for burgers than sandwiches because the approximate minimum cost is $292 for burgers and $250 for sandwiches.

Answer 3

this one takes some thinking.

Answer 4

yeah i dont really understnad what to do

Answer 5

First step is read it, and try to make sense (going on the theory it must mean something)

Answer 6

Look at this part.
The daily cost of making burgers is $520 more than the difference between the square of the number of burgers sold and 30 times the number of burgers sold.

can you translate that into an equation ?

Answer 7

uhmm idk how.i know the 30 is gonna have 30x+520 or something like that

Answer 8

x^2-30x+520?

Answer 9

So my brother kinda explained it and i got the answer D

Answer 10

yes looks good
to avoid confusion, let's use b instead of x
cost(b) = b^2 -30b+520

Answer 11

okay.

Answer 12

forget that, because using b instead of x means I can't write down ax + bx + c
and use -b/(2a) to find the min

so find the min number of burgers by find the x value of the vertex of the equation
x^2-30x+520

Answer 13

is gonna be -30 and 520 correct?

Answer 14

17

Answer 15

a is in front of the x^2 and b is in front of the x (c is +520)

Answer 16

so x and-30 how do i use that into -b/2a

Answer 17

not x, we want only the numbers. remember x^2 is short for 1*x^2

Answer 18

so its gonna be -30/2?

Answer 19

then its gonna be -15?

Answer 20

b is -30
-b is 30
so 15

Answer 21

ohhh okay i got it

Answer 22

15 burgers is where the cost is a min. to find the cost of 15 burgers we use the formula
x^2-30x+520
with x= 15

Answer 23

225-450+520

Answer 24

scratch that 295

Answer 25

so the min cost of the burgers is 295
that is enough info to answer the question

but we could double check, and find the min cost of the sandwiches, using
C(x) = 2x^2 - 40x + 300

Answer 26

C i mean

Answer 27

yes. And if you have time and are not lazy (a bad habit), you would check to see what number you get for the sandwiches. Same idea -b/(2a) to find x.

Answer 28

okay so its gonna be 10 for x

Answer 29

and figure out the cost of 10 sandwiches

Answer 30

so its 100

Answer 31

200-400+300

Answer 32

can you check another questions answer for me please i got it i think but i just need to double check sorry if im bothering you.

Answer 33

yes, which is a double check on choice C. (and good practice)

Answer 34

what is the question?