A28­4Notes.notebook
October 27, 2015
Algebra 2
Ch.8 Notes Page 48
P48 8­4 Properties of Logarithms
Aug 19­6:20 AM
Properties of Logarithms
For any positive numbers, M, N, and b, b ≠ 0
logb MN = logb M + logb N
Product Property
logb M/N = logb M ­ logb N
Quotient Property
logb Mx = xlogb M Power Property
Logs can only be combined if they have the same bases.
Nov 20­7:26 AM
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A28­4Notes.notebook
October 27, 2015
Properties of Logs: Examples
log52 + log56
log28 + log24
3logb4 ­ 3logb2
Nov 20­7:27 AM
Simplifying and Expanding Logs
Write each expression as a single logarithm.
Expand each logarithm.
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A28­4Notes.notebook
October 27, 2015
HW #50
8­4 P457 #1­5,11­15,19­24,28,32
Please put your name and class period at the top of
the homework. Also include the homework number.
Aug 19­6:25 AM
Word Problem Introduction
(Do Not Copy ­ Just Read)
P546
Nov 20­7:28 AM
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A28­4Notes.notebook
October 27, 2015
Example: Noise Reduction
L = 10 log I / I0 L is loudness
I is the intensity of the sound in watts/meter2 I0 is the lowest­Intensity sound that can be heard by an average human.
An airport shipping company wants to decrease the intensity of the sound of the airplanes it uses to 25% of the current level. By how many decibels would the loudness of the sound be decreased?
Let I1 = Present Intensity
Let I2 = Reduced Intensity
Let L1 = Present Loudness
Let L2 = Reduced Loundess
I2 = .25I1
L1 = 10 log I1 / I0 L2 = 10 log I2 / I0 L1 ­ L2 = Nov 20­7:28 AM
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