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3.3 Logarithmic Functions and Their Graphs. The inverse of y = b x is y = log b x. Logarithmic Functions. log b 1 = 0 because b 0 = 1 ex) log 9 1 = log b b = 1 because b 1 = b ex) log 3 3 = log b b y = y because b y = b y ex) log 4 4 2 =
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The inverse of y = bx is y = logbx Logarithmic Functions
logb 1 = 0 because b0 = 1 ex) log9 1 = • logb b = 1 because b1 = b ex) log3 3 = • logbby = y because by = by ex) log4 42 = • blogbx = x because logbx = logbx ex) 7log73 = Logarithmic Basic Properties
log232 • Log9√9 • log644 • 5log517 • log6(1/216) You Try! Evaluate Each Expression
log 1 = 0 because 100 = 1 • log 10 = 1 because 101 = 10 • Log 10y = y because 10y = 10y ex) log 1 = 1000 • 10log x = x because log x = log x ex) 10log(.5) = Common Logarithms (Logs with base 10)
log 9.43 ≈ Check: • log (-14) = You Try! • log 34.5 ≈ Check: Evaluate using calculator & Check
Solving Logarithmic Equations • logx = 2 • Log5 x = -3 You Try! • logx = -1 • Log4 x = 6
logex = lnx y = ln(x) is the inverse of the exponential function y = ex Natural Logarithms : Base e
ln 1 = 0 because e0 = 1 • lne = 1 because e1 = e • lney = y because ey = ey ex) ln e3 = • elnx = x because lnx = lnx ex) eln6 = Natural logarithms
lne-4 • ln 1/e • ln4√e • ln 4.05 ≈ Check: You Try! Evaluate:
h(x) = ln (3 – x) g(x) = ln (x + 2) g(x) = 3 log x h(x) = 1 + log x
Pg. 308-309: 4, 10, 14, 22, 24, 26, 32, 36, 44, 58 Homework