M1410302 - 3.13 SECTION 3.2: LOGARITHMIC (LOG) FUNCTIONS...

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Unformatted text preview: 3.13 SECTION 3.2: LOGARITHMIC (LOG) FUNCTIONS AND THEIR GRAPHS PART A: LOGS ARE EXPONENTS Example Evaluate: log 3 9 Solution The question we ask is: 3 to what exponent gives us 9? log 3 9 = 2 logarithmic form , because 3 2 = 9 exponential form We say: Log base 3 of 9 is 2. Think Zig-zag: Answer: 2. More Examples Log Form Exponential Form log 5 1 5 = 1 5 1 = 1 5 log 9 3 = 1 2 9 1/2 = 9 = 3 log 10 10 7 = 7 10 7 = 10 7 3.14 PART B: COMMON LOGS f x ( ) = log 10 x gives the common log function. It is also written as simply: f x ( ) = log x (A missing log base is implied to be 10.) Your calculator should have the LOG button. Common logs are used in the Richter scale for measuring earthquakes and the pH scale for measuring acidity. Bear in mind that an earthquake measuring a 7 on the Richter scale is 10 times as powerful as one measuring a 6 and 100 times as powerful as one measuring a 5. Negative Richter numbers are also possible....
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This note was uploaded on 09/08/2011 for the course MATH 141 taught by Professor Staff during the Fall '11 term at Mesa CC.

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M1410302 - 3.13 SECTION 3.2: LOGARITHMIC (LOG) FUNCTIONS...

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