Assignment 38 Worksheet no book assignment Common Logarithm How many fingers do we normally have What happens after the number 9 What happens after the number 99 Why is it easier to multiply by 100 that by 99 even though 99 is a smaller number ID: 692357
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11.5 Common Logarithms
By the end of the period, students will be able to use the change of base formula to rewrite logarithms into common logs, and solve equations using common logarithms, as evidenced by completing “Find Someone Who…” worksheet.
Assignment #38
Worksheet, no
book assignmentSlide2
Common Logarithm
How many fingers do we (normally) have?What happens after the number 9?What happens after the number 99?
Why is it easier to multiply by 100 that by 99 even though 99 is a smaller number?
The common log has a BASE of 10.
Since this is our COMMON log we often will write instead of
By the end of the period, students will be able to use the change of base formula to rewrite logarithms into common logs, and solve equations using common logarithms, as evidenced by completing “Find Someone Who…” worksheet.Slide3
Change of Base Formula
Our calculators only have two log buttons
and
(we’ll discuss the other button later).
So if we want to use the calculator to solve log problems, we need to have the logs in
base 10
.
By the end of the period, students will be able to use the change of base formula to rewrite logarithms into common logs, and solve equations using common logarithms, as evidenced by completing “Find Someone Who…” worksheet.
New baseSlide4
Example 1: rewrite each expression using the change of base formula
By the end of the period, students will be able to
use the change of base formula to rewrite logarithms into common logs
, and solve equations using common logarithms, as evidenced by completing “Find Someone Who…” worksheet.Slide5
Example 1: rewrite each expression using the change of base formula
fill in the blanks:
By the end of the period, students will be able to
use the change of base formula to rewrite logarithms into common logs
, and solve equations using common logarithms, as evidenced by completing “Find Someone Who…” worksheet.Slide6
Example 2: Solve each equation using common log
How do we solve
?
Similarly, we can
“take the log of both sides”
This
power of equality
property goes both directions.
Recall that logs and exponents are inverses and will “undo” each other. So if we want to get variable OUT of an exponent we use a log.
By the end of the period, students will be able to use the change of base formula to rewrite logarithms into common logs, and
solve equations using common logarithms, as evidenced by completing “Find Someone Who…” worksheet.Slide7
Example 2: Solve each equation (for
) using common log
By the end of the period, students will be able to use the change of base formula to rewrite logarithms into common logs, and
solve equations using common logarithms
, as evidenced by completing “Find Someone Who…” worksheet.Slide8
Example 2: Solve each equation (for
) using common log
By the end of the period, students will be able to use the change of base formula to rewrite logarithms into common logs, and
solve equations using common logarithms
, as evidenced by completing “Find Someone Who…” worksheet.Slide9
Example 2: Solve each equation (for
) using common log
By the end of the period, students will be able to use the change of base formula to rewrite logarithms into common logs, and
solve equations using common logarithms
, as evidenced by completing “Find Someone Who…” worksheet.Slide10
Find Someone Who…
Instructions:You will not solve a single problem on YOUR paper.
Meet with another person (PAIRS, NOT TRIOS, singles etc. PAIRS!!)
Exchange papers
Look at the unsolved problems on their paper and solve one of your choosing, challenge yourself.Get your paper back and make a new friend
By the end of the period, students will be able to use the change of base formula to rewrite logarithms into common logs, and solve equations using common logarithms, as evidenced by completing
“Find Someone Who…” worksheet
.Slide11
Summary
Which of the following is equivalent to
Using common logarithms, solve
.
By the end of the period, students will be able to use the change of base formula to rewrite logarithms into common logs, and solve equations using common logarithms, as evidenced by completing “Find Someone Who…” worksheet.Slide12
Summary
Which of the following is equivalent to
Using common logarithms, solve
.
By the end of the period, students will be able to use the change of base formula to rewrite logarithms into common logs, and solve equations using common logarithms, as evidenced by completing “Find Someone Who…” worksheet.