Logarithmic Functions and Equations - Complete Interactive Lesson
Part 1: Introduction to Logarithms
📈 Logarithmic Functions
Part 1 of 7 — Logarithm Basics
1. log_b(x) = y means b^y = x
log_b(x) = y means b^y = x
2. Logarithm is the inverse of the exponential function
Logarithm is the inverse of the exponential function
3. Domain
(0, ∞); Range: all real numbers
4. The graph of y = log_b(x) passes through (1, 0) and (b, 1)
The graph of y = log_b(x) passes through (1, 0) and (b, 1)
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Key Concepts Summary
- log_b(x) = y means b^y = x
- Logarithm is the inverse of the exponential function
- Domain: (0, ∞); Range: all real numbers
- The graph of y = log_b(x) passes through (1, 0) and (b, 1)
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Part 2: Properties of Logarithms
Properties of Logarithms
Part 2 of 7 — Properties of Logarithms
1. Product rule
log_b(MN) = log_b(M) + log_b(N)
2. Quotient rule
log_b(M/N) = log_b(M) - log_b(N)
3. Power rule
log_b(M^n) = n · log_b(M)
4. Change of base
log_b(x) = ln(x)/ln(b) = log(x)/log(b)
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Key Concepts Summary
- Product rule: log_b(MN) = log_b(M) + log_b(N)
- Quotient rule: log_b(M/N) = log_b(M) - log_b(N)
- Power rule: log_b(M^n) = n · log_b(M)
- Change of base: log_b(x) = ln(x)/ln(b) = log(x)/log(b)
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Part 3: Solving Logarithmic Equations
Common & Natural Logs
Part 3 of 7 — Common & Natural Logs
1. Common log
log(x) = log₁₀(x), used for pH, decibels, Richter scale
2. Natural log
ln(x) = logₑ(x), used in calculus and natural phenomena
3. ln(e) = 1 and log(10) = 1
ln(e) = 1 and log(10) = 1
4. ln(eˣ) = x and e^(ln(x)) = x for x > 0
ln(eˣ) = x and e^(ln(x)) = x for x > 0
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Key Concepts Summary
- Common log: log(x) = log₁₀(x), used for pH, decibels, Richter scale
- Natural log: ln(x) = logₑ(x), used in calculus and natural phenomena
- ln(e) = 1 and log(10) = 1
- ln(eˣ) = x and e^(ln(x)) = x for x > 0
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Part 4: Change of Base
Solving Logarithmic Equations
Part 4 of 7 — Solving Logarithmic Equations
1. Isolate the logarithmic expression
Isolate the logarithmic expression
2. Convert to exponential form
log_b(x) = y → b^y = x
3. Check for extraneous solutions (argument must be positive)
Check for extraneous solutions (argument must be positive)
4. Use properties to combine or expand log expressions before solving
Use properties to combine or expand log expressions before solving
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Key Concepts Summary
- Isolate the logarithmic expression
- Convert to exponential form: log_b(x) = y → b^y = x
- Check for extraneous solutions (argument must be positive)
- Use properties to combine or expand log expressions before solving
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Part 5: Logarithmic Models
Logarithmic Modeling
Part 5 of 7 — Logarithmic Modeling
1. Richter scale
M = log(I/I₀), each unit is 10× intensity
2. Decibel scale
dB = 10 · log(I/I₀)
3. pH scale
pH = -log[H⁺], logarithmic measure of acidity
4. Logarithmic regression
y = a + b · ln(x) for data modeling
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Key Concepts Summary
- Richter scale: M = log(I/I₀), each unit is 10× intensity
- Decibel scale: dB = 10 · log(I/I₀)
- pH scale: pH = -log[H⁺], logarithmic measure of acidity
- Logarithmic regression: y = a + b · ln(x) for data modeling
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Part 6: Problem-Solving Workshop
Problem-Solving Workshop
Part 6 of 7 — Problem-Solving Workshop
1. Richter scale
M = log(I/I₀), each unit is 10× intensity
2. Decibel scale
dB = 10 · log(I/I₀)
3. pH scale
pH = -log[H⁺], logarithmic measure of acidity
4. Logarithmic regression
y = a + b · ln(x) for data modeling
Check Your Understanding 🎯
Key Concepts Summary
- Richter scale: M = log(I/I₀), each unit is 10× intensity
- Decibel scale: dB = 10 · log(I/I₀)
- pH scale: pH = -log[H⁺], logarithmic measure of acidity
- Logarithmic regression: y = a + b · ln(x) for data modeling
Concept Check 🎯
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Part 7: Review & Applications
Review & Applications
Part 7 of 7 — Review & Applications
1. Richter scale
M = log(I/I₀), each unit is 10× intensity
2. Decibel scale
dB = 10 · log(I/I₀)
3. pH scale
pH = -log[H⁺], logarithmic measure of acidity
4. Logarithmic regression
y = a + b · ln(x) for data modeling
Check Your Understanding 🎯
Key Concepts Summary
- Richter scale: M = log(I/I₀), each unit is 10× intensity
- Decibel scale: dB = 10 · log(I/I₀)
- pH scale: pH = -log[H⁺], logarithmic measure of acidity
- Logarithmic regression: y = a + b · ln(x) for data modeling
Concept Check 🎯
Match the Concepts 🔍