For the second one: $\displaystyle S(x)=\frac {14000\cdot x^2}{7000\cdot x^2+2000}=\frac {14000}{7000+\frac {2000}{x^2}}\longrightarrow \lim_{x\rightarrow\infty}=\frac {14000}{7000+0}=2$
There is a simple typo in that answer.
$\displaystyle S(x)=\frac {14000\cdot x^2}{7\cdot x^2+2000}=\frac {14000}{7+\frac {2000}{x^2}}\longrightarrow \lim_{x\rightarrow\infty}=\frac {14000}{7+0}=2000$