368. Which of the three functions

\[
\begin{aligned}
& y=100 x \\
& y=1000+100 x \\
& y=10000+99 x
\end{aligned}
\]

increases faster than the others?
368. $100(x+h)-100 x=100 h$

$$
[1000+100(x+h)]-(1000+100 x)=100 h \cdot .(2)
$$

$$
[10000+99(x+h)]-(10000+99 x)=99 h . .(3)
$$

The first two increase at the same rate and faster than the third. 369. $\quad[2(x+h)+3]-(2 x+3)=2 h$

$$
\begin{array}{r}
{\left[\frac{1}{2}(x+h)+18\right]-\left[\frac{1}{2} x+18\right]=\frac{1}{2} h} \\
4(x+h)-4 x=4 h \\
{[4(x+h)-4]-(4 x-4)=4 h}
\end{array}
$$

Thus: the functions (3) and (4) increase the fastest and at the same rate, while (2) increases the slowest.