# Math Help - Exponential Functions Question

1. ## Exponential Functions Question

Hi there, I'm trying to do this question but I'm stuck:

Graph the function:
f(x) = (2/3)x, -4
≤x≤1, x∈R

f(-2) lies in the range [1, a]. If a
∈ N, then what is the minimum value of a?

I've drawn the graph, but I don't understand the second part of the question. Could someone please help me?

2. ## Re: Exponential Functions Question

Originally Posted by HelenMc9
Graph the function:
f(x) = (2/3)x, -4≤x≤1, x∈R
f(-2) lies in the range [1, a]. If a ∈ N, then what is the minimum value of a?
I've drawn the graph, but I don't understand the second part of the question. Could someone please help me?
$a = \left\lceil {f( - 2)} \right\rceil$, that is ceiling function.

3. ## Re: Exponential Functions Question

You are asked to find the smallest natural number a such that f(-2) ≤ a.

4. ## Re: Exponential Functions Question

Sorry I don't get it, I'm still really confused ...

5. ## Re: Exponential Functions Question

Originally Posted by HelenMc9
Sorry I don't get it, I'm still really confused ...

What does $f(-2)=~?$

2.25?

7. ## Re: Exponential Functions Question

Originally Posted by HelenMc9
2.25?

OK what is the smallest $a\in\mathbb{N}$ so that $f(-2)\in[1,a]~?$

8. ## Re: Exponential Functions Question

Eh ... I don't know. What does ' f(-2) ∈ [1,a] ' mean? :/

9. ## Re: Exponential Functions Question

Originally Posted by HelenMc9
Eh ... I don't know. What does ' f(-2) ∈ [1,a] ' mean? :/

You cannot do these questions if you don't know the basics

It means $1\le f(-2)\le a$.