The graphs of and both have vertices located at the origin, so we know that there haven't been any translations. However, is somewhat shrunk. This means is less than To get from the graph of to the graph of we need to shrink away from the -axis. Let's look at a point on each graph with the same -values and compare their -values.
As we can see from the graph, when the -value of is three times the -value of the -value is the same for both functions. Therefore, to get must be vertically shrunk by a factor of