Question

Marie is logging the number of radioactive isotopes she observes every minute. She has determined her function to be f(x) = −4x + 120.

Based on the situation above, describe any necessary restrictions to the domain and range. Provide justification for the restrictions.

Answer 1

Well they are talking about minutes so, there is a restriction on the domain

And if the number of radioactive isotopes can only be positive, then there is another restriction on the domain as well as a restriction on the range.

Answer 2

see im so lost -__- they didn't teach me that..:/

Answer 3

so do i need to multiple everything by -1?

Answer 4

@Hero

Answer 5

Oh well when you say she is logging her results, does that mean that \(log_{10}(her\phantom{.}results)=f(x)?\)

Answer 6

huh?.. im so lost..

Answer 7

@KeithAfasCalcLover , I think you're mis-interpreting what "logging" not logs mean.

Answer 8

It said that she was "logging" not "taking logs".

Answer 9

Yeah no I know but then they are asking for the domain of \(10^{120-4x}\) ?

Answer 10

what the front door? i'm so lost ):

Answer 11

@KeithAfasCalcLover , the given function is f(x) = −4x + 120, not anything about logs.

Answer 12

okay @Hero that makes more sense

Answer 13

so how do i describe like restrictions?? do i say how 4x is a negative and it can't be ?

Answer 14

The function is defined as is. You cannot disagree with a clearly defined function. All you have to do is concentrate on figuring out the domain and range.

The domain is all the x values that represent the number of minutes elapsed
The range is all the y values that represent the number of radioactive isotopes remaining in terms of minutes elapsed.

Answer 15

is that it?? @Hero

Answer 16

OOOOOHHHH im sorry @Eternallyfamous , I misinterpreted "logging". My bad.

Answer 17

I'm thinking that the domain is [0, 30]

Which would make the range [0, 120]

Answer 18

I'm not a chemistry major so I'm not really certain, I'm probably on the right track. I hate chemistry.

Answer 19

@Hero This actually isn't chemistry it's algebra 2 ;/

Answer 20

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