1. Today in Precalculus Go over homework
Notes: Intro to Natural Base (you’ll need a calculator)
Homework

2. Natural Base Natural Base is known as e. (e≈2.718 irrational like π)
Named for Leonhard Euler
y = a•ekx
One of the ten basic functions
If k>0, exponential growth
If k<0, exponential decay

3. Natural Base Find the value for the following functions:
y = 3e2x x = 4
y =
y = -5e-3x x = 2
y =

4. Exponential Growth/Decay
State if the following are exponential growth or decay functions.
a) y = e2x b) y = e–2x
c) y = 2–x d) y = 0.6–x
Exponential
Growth (k>0)
Exponential
Decay (k<0)
Exponential Growth
(b>0) but reflected
across y-axis, so decay
Exponential Decay
(0<b<1) but reflected
across y-axis, so growth

5. Graphing y = 2ex-1 Vertical stretch 2 Shift right 1 y = e2x+1
Horizontal shrink ½
Shift up 1

6. Homework
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