Question

Ill medal and its multiple choice.
Cell phone company Y charges a $15 start-up fee plus $0.15 per minute, x. Cell phone company Z charges $0.30 per minute, x, with no start-up fee. Which function represents the difference in cost between Company Y and Company Z?


f(x) = 15x - 0.15


f(x) = -0.15x + 15


f(x) = -0.15x - 15


f(x) = 15x + 0.15

Answer 1

first you need to represent each cost as a function. then you can subtract them to find the answer

Answer 2

so how can we represent "$15 start-up fee plus $0.15 per minute, x" as a function?

Answer 3

15 + .15x

Answer 4

correct, and how about "$0.30 per minute, x, with no start-up fee"

Answer 5

it would just be .30x right

Answer 6

yep :) so now we can subtract them. what's 15 + 0.15x - 0.30x?

Answer 7

15-.15x ?

Answer 8

yes

Answer 9

Thank you !

Answer 10

which can also be written as -0.15x + 15, which is choice b

Answer 11

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