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Algebra 3 Warm-Up 5.3. Solve each equation for x. 3x – 12 = 45 x = 19 2. . x = 39.2. Algebra 3 Lesson 5.3 Objective: SSBAT write and evaluate logarithmic expressions. Standards: 2.1.11A. Review: Addition and Subtraction are opposite operations .
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Algebra 3 Warm-Up 5.3 • Solve each equation for x. • 3x – 12 = 45 • x = 19 • 2. x = 39.2
Algebra 3 Lesson 5.3 Objective: SSBAT write and evaluate logarithmic expressions. Standards: 2.1.11A
Review: Addition and Subtraction are opposite operations. Multiplication and Division are opposite operations. Squaring and Square Rooting are opposite operations.
Solve for x. • 3x= 19683 • You could use guess and check or you can use logarithms. • Logarithms are the opposite of Exponential functions.
Logarithmic Equation • An equation of the form x = logby • y is a positive number Used to solve exponential equations • logb y is read as “log base b of y”
Exponential Form To Logarithmic Form y= bx x= logby ** The base of the Exponent becomes the base of the Logarithm. ** The exponent is all by itself in the logarithm.
Write each in Logarithmic Form 1. 53 = 125 3 = log5 125 5 = log4 1024 2. 45 = 1024 2401 log7 m = 3. 7m = 2401 4 = log12 20736 4. 20736 = 124
5. 100 = 1 0 = log10 1 6.
Change each to Exponential Form • log515625 = 6 • 56 = 15625 • log2 128 = 7 • 27 = 128
Change each to Exponential Form 3. logx2048 = 5.5 x5.5= 2048 4. = ½
Common Logarithm • A logarithm that has a base of 10 • log10 y • You can write it as log y - When there is no base shown it is base 10 log10 15 = log 15 Common Logarithms are used to measure pH (acidity), decibels (sound), Richter Scale (earthquakes)
Since the Common Logarithm log10 is used the most in real world applications it is given a key on the calculator. • Evaluate each. • log10 150 • log 240 • 3. log -13 = 2.176 = 2.380 Undefined
Change of Base Property • Used to evaluate non base 10 logarithms in your calculator. For any positive number M and b, with b ≠ 1 logbM =
Evaluate log2 32 log (32) log (2) = 5
Evaluate each. • log8 16 = 4/3 or 1.333…
log9 27 3. = 1.5 = -.83333
log4 (-600) Answer: Undefined (cannot take the log of a negative number)
On Your Own. • Change to Logarithmic Form • Change to Exponential Form • 3. Evaluate. Show the change of base form. log81 3 = ¼ 811/4 = 3 log2 8
Homework Worksheet 5.2