Logarithmic Functions and Graphs
Sketch Logarithmic Graphs Use Log Properties Objective Sketch Logarithmic Graphs Use Log Properties
Relevance Log functions are useful for modeling data that represent quantities that increase or decrease slowly. For example, a log function can model the minimum required ventilation rates in public school classrooms.
Warm Up – Make Some Observations
Annually Monthly Quarterly Continuously Warm Up - If $5,000 is invested at an interest rate of 5% per year, find the amount of the investment at the end of 5 years for the following compounding methods: Annually Monthly Quarterly Continuously
Annually: Monthly:
Quarterly: Continuously
Warm Up Solve: Find the Vertex:
Logarithmic Functions
Logarithmic Function It’s the inverse of the exponential function Switch the x’s and the y’s!
Logarithmic Function Used to find unknown exponents in exponential models. Logs define many measurement scales in the sciences: 1) ph 2) decibal 3) Richter scale
For any positive base b, where b≠1: bx = y if and only if x = logby Exponential Form Logarithmic Form
Write in logarithmic form.
Write in logarithmic form.
Write in logarithmic form.
Write in exponential form.
Write in exponential form.
Write in exponential form.
Graphing Log Functions
Graph: Is the inverse of Domain: Range: Domain: Range:
Graph: Up 3 from previous example! Domain: Range:
Left 4 from Original Example! Graph: Left 4 from Original Example! Domain: Range:
Right 2 from Original Example! Graph: Right 2 from Original Example! Domain: Range:
Graph: Reflected over y-axis. Domain: Range:
Graph: Reflected over x-axis. Domain: Range:
Solving Log Functions
Find the value of x.
Find the value of x.
Find the value of x.
Find the value of x.
Find the value of x.
Find the value of x.
Find the value of x.
Find the value of x.
Find the value of x.
Natural Log
Natural log
The Natural Logarithmic Function is the inverse of the natural exponential function Function Inverse
Write in logarithmic form.
Write in exponential form.
Find the value of x.
Using Calculator
Solve
Find to the nearest thousandth – using the calculator.
Find to the nearest thousandth – using the calculator.
Find to the nearest thousandth – using the calculator.