1. Exponential Functions
ALGEBRA 1 LESSON 8-7
Evaluate each exponential function.
a. y = 3x for x = 2, 3, 4
x y = 3x y
2 32 = 9 9
3 33 = 27 27
4 34 = 81 81
b. p(q) = 3 • 4q for the domain {–2, 3}
q p(q) = 3 • 4q p(q)
–2 3 • 4–2 = 3 • = 1 16 3
3 3 • 43 = 3 • 64 =
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2. Exponential Functions
ALGEBRA 1 LESSON 8-7
Suppose two mice live in a barn. If the number of mice quadruples every 3 months, how many mice will be in the barn after 2 years?
ƒ(x) = 2 • 4x
ƒ(x) = 2 • 48
In two years, there are 8 three-month time periods.
ƒ(x) = 2 • 65,536
Simplify powers.
ƒ(x) = 131,072
Simplify.
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3. Exponential Functions
ALGEBRA 1 LESSON 8-7
Graph y = 2 • 3x.
2 2 • 32 = 2 • 9 = 18 (2, 18)
x y = 2 • 3x (x, y)
–2 2 • 3–2 = = (–2, ) 2
3 2 9
–1 2 • 3–1 = = (–1, ) 2 31 3
0 2 • 30 = 2 • 1 = 2 (0, 2)
1 2 • 31 = 2 • 3 = 6 (1, 6)
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4. Exponential Functions
ALGEBRA 1 LESSON 8-7
The function ƒ(x) = 1.25x models the increase in size of an image being copied over and over at 125% on a photocopier. Graph the function.
x ƒ(x) = 1.25x (x, ƒ(x))
= (1, 1.3)
= (2, 1.6)
= (5, 3.1)
= (4, 2.4)
= (3, 2.0)
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5. Exponential Functions
ALGEBRA 1 LESSON 8-7
1. Evaluate each function rule for the given value.
a.  y = 0.5x for x = 3
b.  ƒ(x) = 4 • 3x for x = –2
2. Suppose an investment of $5000 doubles every 12 years.
a.  How much is the investment worth after 24 years?
b.  After 48 years?
0.125
4 9
$20,000
$80,000
3. Graph y = 0.5 • 3x.
4. Graph y = –0.5 • 3x.
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