AP Precalculus -2.2 Linear and Exponential Change- MCQ Exam Style Questions - Effective Fall 2023
AP Precalculus -2.2 Linear and Exponential Change- MCQ Exam Style Questions – Effective Fall 2023
AP Precalculus -2.2 Linear and Exponential Change- MCQ Exam Style Questions – AP Precalculus- per latest AP Precalculus Syllabus.
Question
(B) \[\begin{array}{c|c} x & y \\ \hline 5 & 30 \\ 6 & 42 \\ 7 & 56 \\ 8 & 72 \\ \end{array}\]
(C) \[\begin{array}{c|c} x & \ln y \\ \hline 1 & 1 \\ 2 & 3 \\ 3 & 9 \\ 4 & 27 \\ \end{array}\]
(D) \[\begin{array}{c|c} x & \ln y \\ \hline 5 & 50 \\ 6 & 60 \\ 7 & 70 \\ 8 & 80 \\ \end{array}\]
▶️ Answer/Explanation
A function is exponential if the natural logarithm of its output values \( \ln y \) is linear in \( x \).
In option (C), \( \ln y \) values are 1, 3, 9, 27 — these are not linear in \( x \).
In option (D), \( \ln y \) values are 50, 60, 70, 80 — these form an arithmetic sequence, so \( \ln y \) is linear in \( x \).
Thus \( y = e^{mx+b} \) is exponential.
✅ Answer: (D)
Question
(B) The output values of \( f \) only, not \( g \), are proportional over equal-length input-value intervals.
(C) The output values of \( g \) only, not \( f \), are proportional over equal-length input-value intervals.
(D) The output values of neither \( f \) nor \( g \) are proportional over equal-length input-value intervals.
▶️ Answer/Explanation
Exponential functions \( g(x) = a \cdot b^x \) have outputs that are proportional over equal-length input intervals (ratio constant).
Adding a constant \( +4 \) to \( g \) gives \( f(x) \), which is no longer a pure exponential; its successive ratios are not constant.
Thus only \( g \) has proportional output changes over equal-length input intervals.
✅ Answer: (C)
