3/21/2017
Reminders: Today is 3/20 & 3/21
• Unit 9 Exam Monday 3/27 (A) & Tuesday 3/28 (B)
• English EOC I Tuesday 3/28
• English EOC II Thursday 3/30
Monday
Tuesday
Wednesday
Thursday
Friday
Saturday
7:30-8:15am
7:30-8:15am
7:30-8:15am
7:30-8:15am
7:30-8:15am
9am-12pm
Advisory 9th & 11th
Grades
Advisory 9th &
10th Grades
Advisory 9th,
10th, & 11th
Grades
Advisory 10th, &
11th Grades
4:00 – 4:50pm
4:00 – 4:50pm
4:00 – 4:50pm
Lesson 9.5
SWBAT evaluate logs using
change of base formula.
From textbook: 8-3, p.454-457; 8-4, p.462-467
Online text: 7-5, 7-6
3/21/2017
IV. Change of Base Formula
A. Problem: How to evaluate log 27 ?
1. Change of Base Formula: For any positive numbers, M, b and c, with
1 and
1,
2. Used for:
a) Evaluating when you cannot get same bases
b) Converting into different bases
c) “c” can be common base for b and M or 10
3. Example 2:
a) Evaluate log 32
b) Evaluate
15 then convert
15 to a logarithm in base 2
V. Common logarithms –uses base 10, written as just log
1. Scientists use common logs to measure acidity or pH
2. Acidity increases as concentration of hydrogen ions increases
3. pH
log H
4. Examples:
a) pH lemon juice 2.3 and pH of milk is 6.6. Find concentration of
and which is more acidic?
b) Concentration of
in seawater with pH 8.5
in each
3/21/2017
Your turn. Snap to it!
Evaluate using change of base
1) log 49
2)
log 2.659
Convert to base 8 (round to nearest thousandth)
3) log 49
Find the concentration of
with 2 significant figures
5) Condensed milk 6.3
4)
log 2.659
given the pH write in scientific notation
Agenda
•Do Now
•Lecture
•Guided Practice
•Independent Practice
•Exit Ticket
•Closing
6) Soy sauce 4.9
3/21/2017
Independent Practice –20 minutes
•Silently and independently: if you have a question,
raise your hand. If I am speaking with another student,
you may quietly ask your elbow partner
•If you are completely lost, go to back board.
•When complete, I will sign your paper. You may begin
the exit ticket
Evaluate using change of base Round to nearest thousandth
1) log 49
2) log 2.659
3. Convert #1 into base 8
Round to nearest thousandth
Find the concentration of
significant figures
5. Maple syrup 3.2
4. Convert #2 into base 8
Round to nearest thousandth
given the pH write in scientific notation with 2
6. Egg white 8.0