# Thread: I need help with the domain of a exponential problem

1. ## I need help with the domain of a exponential problem

The exponential function shown in the graph models the sequence 1,1/3,1/9,1/27, ... What is the domain of the function?

A)(0, ∞)
B) [0, ∞)
C) {0, 1, 2, 3, ...}
D) {1, 2, 3, ...}

The Graph is y=3^-x

2. Originally Posted by landonjones6
The exponential function shown in the graph models the sequence 1,1/3,1/9,1/27, ... What is the domain of the function?

A)(0, ∞)
B) [0, ∞)
C) {0, 1, 2, 3, ...}
D) {1, 2, 3, ...}

The Graph is y=3^-x
is the graph of the function discrete or continuous?

3. Originally Posted by skeeter
is the graph of the function discrete or continuous?
I think its continuous because it says " the sequence 1, 1/3, 1/9, 1/27..." i think the dot dot dot represents that it continues

4. Originally Posted by landonjones6
I think its continuous because it says " the sequence 1, 1/3, 1/9, 1/27..." i think the dot dot dot represents that it continues
is the graph a solid curve or a series of disconnected points?

5. Originally Posted by skeeter
is the graph a solid curve or a series of disconnected points?
the graph looks like a regular y=3^-x

6. imho, the question is ambiguous. from what you say, you are shown a continuous graph of the function $\displaystyle y = 3^{-x}$ (shown in black), but the question says the function models the discrete sequence 1 , 1/3 , 1/9 , ... (the red dots).

the domain of the continuous function is $\displaystyle [0, \infty)$

the domain of the discrete function is $\displaystyle \{0,1,2,3,...\}$

7. Originally Posted by skeeter
imho, the question is ambiguous. from what you say, you are shown a continuous graph of the function $\displaystyle y = 3^{-x}$ (shown in black), but the question says the function models the discrete sequence 1 , 1/3 , 1/9 , ... (the red dots).

the domain of the continuous function is $\displaystyle [0, \infty)$

the domain of the discrete function is $\displaystyle \{0,1,2,3,...\}$
the other side of the graph is also shown

8. Originally Posted by landonjones6
the other side of the graph is also shown
looking at the answer choices, that would not matter. (none include negative values) ... is this one of those "online" course questions?

9. Originally Posted by skeeter
looking at the answer choices, that would not matter. (none include negative values) ... is this one of those "online" course questions?
yes it is

10. thought so ...

I would go with the domain of the discrete function since they made a point of of listing the discrete members of the sequence. I can't guarantee that's what they're looking for, so the final decision, of course, is yours.