1. **State the problem:** We are given an exponential graph with a point (0,5) and asked to find the exponential function $f(x)$, including the initial value and constant ratio.
2. **Recall the general form of an exponential function:**
$$f(x) = a \cdot r^x$$
where $a$ is the initial value (value at $x=0$) and $r$ is the constant ratio (base of the exponential).
3. **Identify the initial value:**
From the point $(0,5)$, when $x=0$, $f(0) = a \cdot r^0 = a = 5$.
So, the initial value $a = 5$.
4. **Find the constant ratio $r$:**
We need another point on the graph to find $r$. The graph shows rapid increase, and from the description, let's use $x=2$ and estimate $f(2)$ from the graph.
Assuming $f(2) = 20$ (approximate from the graph).
5. **Use the point $(2,20)$ to find $r$:**
$$f(2) = 5 \cdot r^2 = 20$$
Divide both sides by 5:
$$\frac{5 \cdot r^2}{\cancel{5}} = \frac{20}{5} \Rightarrow r^2 = 4$$
6. **Solve for $r$:**
$$r = \sqrt{4} = 2$$
7. **Write the exponential function:**
$$f(x) = 5 \cdot 2^x$$
**Final answer:** The exponential function is $f(x) = 5 \cdot 2^x$ with initial value 5 and constant ratio 2.
Exponential Function B2A117
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