1. **State the problem:** We are given the exponential function $$y = 1100(1.48)^{-7x}$$ and need to determine if it represents growth or decay, and find the percentage rate of increase or decrease per unit of $x$ to the nearest tenth of a percent.
2. **Recall the general form:** An exponential function can be written as $$y = a b^x$$ where:
- $a$ is the initial value,
- $b$ is the base that determines growth or decay.
3. **Identify growth or decay:**
- If $b > 1$, the function represents exponential growth.
- If $0 < b < 1$, the function represents exponential decay.
4. **Rewrite the base:**
Given $$y = 1100(1.48)^{-7x}$$, rewrite the base as:
$$ (1.48)^{-7} = \frac{1}{(1.48)^7} $$
Calculate $(1.48)^7$:
$$ (1.48)^7 \approx 1.48^7 = 1.48 \times 1.48 \times 1.48 \times 1.48 \times 1.48 \times 1.48 \times 1.48 \approx 37.59 $$
So,
$$ (1.48)^{-7} = \frac{1}{37.59} \approx 0.0266 $$
5. **Rewrite the function:**
$$ y = 1100 (0.0266)^x $$
6. **Interpretation:**
Since the base $0.0266$ is less than 1, the function represents exponential decay.
7. **Calculate the percentage rate of decrease:**
The rate of decrease per unit $x$ is:
$$ (1 - 0.0266) \times 100\% = 0.9734 \times 100\% = 97.34\% $$
Rounded to the nearest tenth:
$$ 97.3\% $$
**Final answer:** The function represents exponential decay with a percentage rate of decrease of approximately **97.3%** per unit of $x$.
Exponential Growth Decay C4392D
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