Marshall's mistake lies in his understanding of the growth rates of the two functions over their entire domains. The correct response is:
Marshall is only considering a small portion of the domains of the functions. If he went farther to the right on the graph, he would observe that the growth rate of f(x)=6(1.5)^x eventually surpasses the growth rate of g(x)=5x+10 for large values of x.
This means that while \(g(x)\) may initially be greater for certain values of \(x\) (especially for smaller \(x\)), the exponential function \(f(x)\) will eventually grow at a faster rate and surpass \(g(x)\) as \(x\) increases. Thus, he is not recognizing the long-term behavior of the exponential function compared to the linear function.