Algebra I: Lesson Plan * 10/30/2006

Quickstart
Checkpoint Quiz #2 p.267

Lesson
12-1: Inverse Variation Objective: To solve inverse variations using the correct operations and to use graphs and tables to compare inverse and direct variation.

Investigation: Inverse Variation p.636
Think-Pair-Share

Definition: Inverse Variation p.637
An equation in the form xy = k or y = k/x, where k ≠ 0, is an inverse variation.
The constant of variation is k.

Example 1: Writing an equation in inverse variation given a point
Check Understanding #1
Example 2: Find the missing coordinate

Key Concept: Summary - Direct and Inverse Variation
Direct Variation
y = kx
Graph is an increasing straight line.
y varies directly with x.
y is directly proportional to x.
the ration y/x is constant

Inverse Variation
y = k/x
Graph is a decreasing curve.
y varies inversely with x.
y is inversely proportional with x.
The product xy is constant.

Example 4: Determining direct or inverse variation
Example 5: Real-World Problem Solving

Math in the Media
p.641 #44

6-1 Rate of Change and Slope Objective: To solve problems by finding the rate of change and to find slope using a coordinate plane.

Investigation: Exploring Rate of Change p.282

Ski lifts are used to transport skiers up ski slopes.
Slope is rate of change,
the change in the dependent variable compared to the change in the independent variable.

Example 3: Finding Slope Using a Graph

Formula
Slope = rise / run = (y₂ - y₁) / (x₂ - x₁), where x₂ - x₁ ≠ 0

Homework
p.640 - 641 #3 - 45 x 3's