Solving Systems with Elimination (Lesson 6.3)
Unit 0: Prerequisites
Day 1: The Cartesian Plane
Day 2: Equations of Circles
Day 3: Solving Equations in Multiple Representations
Day 4: Reasoning with Formulas
Day 5: Quiz 0.1 to 0.4
Day 6: Linear Relationships
Day 7: Reasoning with Slope
Day 8: Set Notation
Day 9: Quiz 0.5 to 0.7
Day 10: Unit 0 Review
Day 11: Unit 0 Test
Unit 1: Functions
Day 1: Functions and Function Notation
Day 2: Domain and Range
Day 3: Rates of Change and Graph Behavior
Day 4: Library of Parent Functions
Day 5: Transformations of Functions
Day 6: Transformations of Functions
Day 7: Even and Odd Functions
Day 8: Quiz 1.1 to 1.6
Day 9: Building Functions
Day 10: Compositions of Functions
Day 11: Inverse Functions
Day 12: Graphs of Inverse Functions
Day 13: Piecewise Functions
Day 14: Quiz 1.7 to 1.11
Day 15: Unit 1 Review
Day 16: Unit 1 Test
Unit 2: Polynomial and Rational Functions
Day 1: Connecting Quadratics
Day 2: Completing the Square
Day 3: Polynomials in the Short Run
Day 4: Polynomials in the Long Run
Day 5: Review 2.1-2.4
Day 6: Quiz 2.1 to 2.4
Day 7: Factor and Remainder Theorem
Day 8: Factor and Remainder Theorem
Day 9: Complex Zeros
Day 10: Connecting Zeros Across Multiple Representations
Day 11: Intro to Rational Functions
Day 12: Graphing Rational Functions
Day 13: Quiz 2.5 to 2.9
Day 14: Unit 2 Review
Day 15: Unit 2 Test
Unit 2: Linear Algebra
Unit 3: Exponential and Logarithmic Functions
Day 1: Exponential Functions
Day 2: Graphs of Exponential Functions
Day 3: Compound Interest and an Introduction to "e"
Day 4: Review 3.1-3.3
Day 5: Quiz 3.1 to 3.3
Day 6: Logarithmic Functions
Day 7: Graphs of Logarithmic Functions
Day 8: Logarithm Properties
Day 9: Solving Exponential and Logarithmic Equations
Day 10: Quiz 3.4 to 3.7
Day 11: Exponential and Logarithmic Modeling
Day 12: Unit 3 Review
Day 13: Unit 3 Test
Unit 4: Trigonometric Functions
Day 1: Right Triangle Trig
Day 2: Inverse Trig Ratios
Day 3: Radians and Degrees
Day 4: Unit Circle
Day 5: Unit Circle
Day 6: Other Trig Functions
Day 7: Review 4.1-4.6
Day 8: Quiz 4.1 to 4.6
Day 9: Graphing Sine and Cosine
Day 10: Transformations of Sine and Cosine Graphs
Day 11: Graphing Secant and Cosecant
Day 12: Graphing Tangent and Cotangent
Day 13: Quiz 4.7 to 4.10
Day 14: Inverse Trig Functions
Day 15: Trigonometric Modeling
Day 16: Trigonometric Identities
Day 17: Unit 4 Review
Day 18: Unit 4 Review
Day 19: Unit 4 Test
Unit 5: Applications of Trigonometry
Day 1: Law of Sines
Day 2: The Ambiguous Case (SSA)
Day 3: Law of Cosines
Day 4: Area and Applications of Laws
Day 5: Vectors
Day 6: Review 5.1-5.5
Day 7: Quiz 5.1 to 5.5
Day 8: Polar Coordinates
Day 9: Equations in Polar and Cartesian Form
Day 10: Polar Graphs Part 1
Day 11: Polar Graphs Part 2
Day 12: Review 5.6-5.9
Day 13: Quiz 5.6 to 5.9
Day 14: Parametric Equations
Day 15: Parametric Equations (With Trig)
Day 16: Unit 5 Review
Day 17: Unit 5 Test
Unit 6: Systems of Equations
Day 1: What is a Solution?
Day 2: Solving Systems with Substitution
Day 3: Solving Systems with Elimination
Day 4: Review 6.1-6.3
Day 5: Quiz 6.1 to 6.3
Day 6: Solving Systems in 3 Variables
Day 7: Solving Systems in 3 Variables
Day 8: Partial Fractions
Day 9: Unit 6 Review
Day 10: Unit 6 Test
Unit 7: Sequences and Series
Day 1: Introducing Sequences
Day 2: Using Sequences and Series to Describe Patterns
Day 3: Arithmetic Sequences and Series
Day 4: Review 7.1-7.2
Day 5: Quiz 7.1 to 7.2
Day 6: Geometric Sequences and Finite Series
Day 7: Infinite Geometric Sequences and Series
Day 8: Proof by Induction
Day 9: Proof by Induction
Day 10: Quiz 7.3 to 7.5
Day 11: Unit 7 Review
Day 12: Unit 7 Test
Unit 8: Limits
Day 1: What is a Limit?
Day 2: Evaluating Limits Graphically
Day 3: Evaluating Limits with Direct Substitution
Day 4: Evaluating Limits Analytically
Day 5: Evaluating Limits Analytically
Day 6: Review 8.1-8.4
Day 7: Quiz 8.1 to 8.4
Day 8: Continuity
Day 9: Continuity
Day 10: Intermediate Value Theorem
Day 11: Intermediate Value Theorem
Day 12: Review 8.5-8.6
Day 13: Quiz 8.5 to 8.6
Day 14: Limits at Infinity
Day 15: Unit 8 Review
Day 16: Unit 8 Test
Unit 9: Derivatives
Day 1: Introduction to Derivatives
Day 2: Average versus Instantaneous Rates of Change
Day 3: Calculating Instantaneous Rate of Change
Day 4: Calculating Instantaneous Rate of Change
Day 5: The Derivative Function
Day 6: The Derivative Function
Day 7: Review 9.1-9.3
Day 8: Quiz 9.1 to 9.3
Day 9: Derivative Shortcuts
Day 10: Differentiability
Day 11: Connecting f and f’
Day 12: Connecting f and f’
Day 13: Review 9.4-9.6
Day 14: Quiz 9.4 to 9.6
Day 15: Derivatives of Sine and Cosine
Day 16: Product Rule
Day 17: Quotient Rule
Day 18: Review 9.7-9.9
Day 19: Quiz 9.7 to 9.9
Day 20: Unit 9 Review
Day 21: Unit 9 Test
Unit 10: (Optional) Conic Sections
Day 1: Intro to Conic Sections
Day 2: Defining Parabolas
Day 3: Working with Parabolas
Day 4: Quiz 10.1 to 10.3
Day 5: Defining Ellipses
Day 6: Working with Elllipses
Day 7: Defining Hyperbolas
Day 8: Working with Hyperbolas
Day 9: Quiz 10.4 to 10.7
Day 10: Unit 10 Review
Day 11: Unit 10 Test
Learning Targets
Explain the method of elimination using scaling and comparison
Determine the conditions that result in dependent, independent, and inconsistent systems
Connect contextual, graphical, and analytical representations of dependent, independent, and inconsistent systems
Tasks/Activity | Time |
---|---|
Activity | 20 minutes |
Debrief Activity | 10 minutes |
Important Ideas | 5 minutes |
Check Your Understanding | 15 minutes |
Activity: How much for a Bagel and Cream Cheese?
Lesson Handouts
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Answer Key
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Homework
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Experience First
In this lesson students look at various Panera orders to determine the price of a tub of cream cheese and a bagel. Questions 1-3 introduce the context of Panera Bread orders and conceptualize the idea of a solution as well as the number of solutions. Most students use their own experiences at bakeries to suggest a reasonable price for a bagel or tub of cream cheese, and then solve for the remaining
variable. Students realize in question 1 that having one order is insufficient to determine the cost of each order. Choosing any price of bagel would allow students to solve for the necessary price of a tub of cream cheese, or vice versa. In question 2, students must identify the fact that the number of bagels and tubs of cream cheese purchased by Kelly is exactly half the number of bagels and tubs of cream cheese purchased by Peyton, so it follows that Kelly’s order should be exactly 1⁄2 the cost of Peyton’s order. Students learn that scaled versions of an equation produce an equivalent equation, which is still a true equation, but it does not provide additional information that would allow us to narrow down the cost of a bagel or tub of cream cheese. Finally, in question 4, students receive Carter’s order which is an independent equation. The question is worded intentionally so they will compare Carter’s order to twice Peyton’s order. The difference in price between twice Peyton’s order and Carter’s order must be the price of 3 bagels, since otherwise the orders are the same! This is the idea of elimination--scaling the equations so that the only difference in price can be attributed to one variable. It’s important that students understand this conceptually instead of just going through the rote procedure of multiplying equations by a scalar and then adding or subtracting equations. While students leave Algebra 2 feeling pretty confident using elimination as a strategy, we want students to be able to connect this method with important ideas about equivalence.
Formalize Later
This experience reveals the big idea of elimination: creating equivalent equations by scaling so that the only remaining difference between the two equations can be attributed to one variable. The debrief should push students to articulate why they would compare Carter's order to twice Peyton's order. The debrief will also add the vocabulary words of "dependent system" and tie this to a system having infinitely many solutions and equations in the system being equivalent. The Important Ideas section ties together graphical and analytical representations of dependent, independent, and inconsistent systems. Students should be able to reason about systems of linear equations from the perspective of slopes and y-intercepts, as well as equivalent equations and scalar multiples. Questions 3 and 4 on the Check Your Understanding encourage students to strategically assess what conditions are needed to classify a system as independent, dependent, or inconsistent. This understanding is a critical piece of the open middle task on day 5.