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5.5 Logarithms. 5.5 Logarithms. Objectives: I will be able to… Rewrite equations between exponential and logarithmic forms Evaluate logarithms Solve logarithms Vocabulary: logarithms, natural logarithms. Why learn about logarithms?. 5.1-5.4 were all about exponents
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5.5 Logarithms Objectives: I will be able to… • Rewrite equations between exponential and logarithmic forms • Evaluate logarithms • Solve logarithms Vocabulary: logarithms, natural logarithms
Why learn about logarithms? • 5.1-5.4 were all about exponents • A logarithm is the inverse of an exponent • We can use logarithms to solve for a missing exponential value
Logarithmic Function exponent x and b are ALWAYS POSITIVE y can be + or - We discovered last week that exponential functions followed the same translation rules as polynomials. We can switch between these two forms to assist us in solving problems. number base
Rewrite Exponents ⟶ Logs x = 216 b = 6 a=3 x = .01 a=-2 b = 10 x = .0498 a=-3 b= e
Logarithmic Function Solve for the missing variable by changing to exponential form.log5 c = 3 loga64 = 2 log7= w c 64 125 c a ± 8 w -2
Logarithmic Function Two special types of logarithms: • Common Log • No b means base 10 • Natural Log • ln means base e
Logarithmic Function =y .01 -2 Evaluate: If not an equation, let log equal y as in general form. No base means base 10. Evaluate: =y =y =y e 10 y Remember number and base can not be negative. y
Logarithmic Function Solve for x using logarithm and exponent rules. Change form of logarithm. Change form of 729. Use exponent rules. Not matching exponents, must get rid of exponent with x.
Homework pg. 194 #1-7 odd, 12, 14, 17
Exit Ticket 1. Rewrite the following log functions into exponential form: a) b) • Solve for x. a) b)
Homework- Day 2 pg. 196-197 #36-42 even, 47