Chapter 4 - Exponential Functions - 4.2 Comparing Exponential and Linear Functions - Exercises and Problems for Section 4.2 - Exercises and Problems - Page 154: 1

$P_A$, $P_B$, $P_C$ increase $P_D$ decreases

Given The following functions are changing exponentially. \begin{equation} \begin{aligned} P_B&=270\cdot (1.021)^{t}\\ P_C&=150\cdot (1.045)^{t}\\ P_D&=600\cdot (0.978)^{t} \end{aligned} \end{equation} The function $P_A$ increases in time because it is linear with positive slope, the functions $P_B$ and $P_C$ increase in time because they have a base greater than $1$, while the function $P_D$ decreases since its base is between $0$ and $1$.