Question

I need some help please. Write a function rule to describe each statement...
the cost in dollars of printing dollar bills when it costs 3.8cents to print a dollar bill.

the amount of money you earn mowing lawns at $15 per lawn.

the profit you make selling flowers at $1.50 each when each flower costs you $.80

Answer 1

it costs 3.8 cents to print 1 dollar

its costs 2 times 3.8 cents to print two dollars

it costs 3 times 3.8 cents to print 3 dollars

you can see a pattern here right?

Answer 2

yeah,but how do i write them as function rules?

Answer 3

we use variables!

there should be two of them; one will represent the number of dollars, lets call that x and the other will represent the cost to print them, lets call that y

Answer 4

my teacher told me to write the functions as f(x)=...

Answer 5

ok lets use f(x) instead of y

so the cost to print, f(x), should equal the number of dollars, x, times 3.8 cents

Answer 6

so f(x)=3.8x

Answer 7

yes

Answer 8

ok so then for the second one would it be... f(x)=$15x

Answer 9

yep

Answer 10

but actually I made a mistake on the first one

Answer 11

I d dont understand how to write the third one though.

Answer 12

the function for the first part should give us the cost in dollars, with f(x) = 3.8x we'll end up with the number of cents

Answer 13

so you just convert 3.8 cents into dollars which should be .038

Answer 14

the profit you make selling flowers at $1.50 each when each flower costs you $.80

Answer 15

what is the profit if I sell one flower?

Answer 16

70 cents

Answer 17

right..
and if i sell two flowers?

Answer 18

a dollar and 40 cents

Answer 19

which is the same as 2 times 70 cents right?

if I sell 3 flowers the profit would be 3 times 70 cents

and if I sell x flowers the profit will be x times 70 cents

Answer 20

ok so... would the function be f(x)=.70x?

Answer 21

yes! good job

Answer 22

Thanks. Now i have another question i have this equation... f(x)=$0.59x where x+number of pounds. if i had $10 to buy that turkey how big a turkey could i buy?

Answer 23

you have f(x) = $0.59x which in words is, the cost of a turkey, f(x), is the number of pounds, x, times 59 cents

Answer 24

so the cost of a turkey is a function of the number of pounds that it weighs, does that make sense so far?

Answer 25

yeah. i was wondering where you d plug in the $10.

Answer 26

the ten dollars goes where dollars is represented in the equation

Answer 27

x is pounds
f(x) is dollars

so the equation, when we put in 10 dollars, becomes

$10 = $0.59x

Answer 28

and by solving for x you will have found out how big a turkey you could by with 10 dollars

Answer 29

does that make sense?

Answer 30

16.95lb. is what i got. Yeah it does make sense.