Use exponent rules to rewrite exponential functions β converting horizontal shifts and dilations into equivalent vertical forms.
π Core Idea
The exponent properties you learned in algebra can also be used to manipulate and rearrange exponential functions into equivalent forms β turning horizontal transformations into vertical ones, and vice versa.
π Review of Important Exponent Rules
Product Property
bm Β· bn = bm+n
53 Β· 58 = 511
2x Β· 23 = 2x+3
Power Property
(bm)n = bmn
(53)x = 53x
(2x)3 = 23x
Negative Exponent
bβn = 1 / bn
xβ3 = 1/x3
xβΒ½ = 1/βx
π Horizontal Translation β Vertical Dilation
Using the Product Property
A horizontal shift of an exponential function can always be rewritten as a vertical dilation using the Product Property in reverse.
f(x) = 4x+2
= 4x Β· 42
= 16 Β· 4x
Important Idea: Every horizontal translation bx+h is equivalent to a vertical dilation a Β· bx, where a = bh.
βοΈ Example 1 β Identify the Horizontal Transformation
Part a
f(x) = 4x+2
Shifted left 2 units
Part b
g(x) = 2x/3
Horizontal dilation by β
Part c
h(x) = 92x
Horizontal dilation by 2
Part d
k(x) = 5xβ1
Shifted right 1 unit
βοΈ Example 2 β Rewrite as Vertical Dilation (No Horizontal Shift)
f(x)
2x+3
= 23 Β· 2x = 8 Β· 2x
g(x)
3xβ2
= 3β2 Β· 3x = β Β· 3x
k(x)
4 Β· 3x+2
= 4 Β· 9 Β· 3x = 36 Β· 3x
π Horizontal Dilation β Base Change
Using the Power Property
A horizontal dilation of an exponential function bcx is equivalent to changing the base using the Power Property.
f(x) = bcx = (bc)x
For example:
y = 92x = (92)x = 81x
βοΈ Examples 3 & 4 β Multiple Choice
Which is an equivalent form of y = 2 Β· 9x?
(A) f(x) = 3x
(B) f(x) = 3 Β· 9x
(C) f(x) = 18x
β (D) f(x) = 2 Β· (32)x = 2 Β· 9x
Which is an equivalent form of y = 9 Β· 4x?
(A) f(x) = 23 Β· 16x
(B) f(x) = 23 Β· 16x
β (C) f(x) = 9 Β· 4x = 9 Β· (22)x
(D) f(x) = 9 Β· 16x
Card 1 of 4
Concept
What is the Product Property of Exponents?
Tap to reveal answer β¨
Answer
bm Β· bn = bm+n
When multiplying powers with the same base, add the exponents. Example: 53 Β· 58 = 511
Topic 2.4
Exponential Manipulation Quiz
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Question 1 of 4
Which of the following is an equivalent form of f(x) = 4x+2 that has a vertical dilation and no horizontal translation?
Question 2 of 4
Using the Power Property, which of the following is equivalent to y = 92x?
Question 3 of 4
Rewrite g(x) = 3xβ2 in the form a Β· 3x. What is the value of a?
Question 4 of 4
Which of the following is an equivalent form of f(x) = 4 Β· 3x+2 with no horizontal translation?
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