The image shows a mathematical problem asking to identify the function represented by the graph. The options given are:

1. $f(x) = 0.5x + 5.5x^2$
2. $f(x) = \sqrt{5x}$
3. $f(x) = 5^x$
4. $f(x) = \log(5x)$

The graph appears to be an exponential curve that increases rapidly, suggesting that the function might involve an exponential term.

Given the nature of the graph, the best matching function from the options is likely:

$f(x) = 5^x$

This is because the graph shows an exponential increase, which is characteristic of functions of the form $a^x$ where $a > 1$.

Would you like more details on how this was determined, or do you have any questions? Here are some related questions:

1. What are the key characteristics of exponential functions?
2. How can you differentiate between different types of functions using their graphs?
3. What does the function $f(x) = \sqrt{5x}$ look like graphically?
4. How does the logarithmic function $f(x) = \log(5x)$ differ from exponential functions?
5. How would you determine the equation of a graph if no options were provided?

Tip: When identifying functions from graphs, focus on the general shape and behavior of the curve, such as whether it increases or decreases and how rapidly it does so.