Algebra 1 Online! Henrico County Public Schools, Virginia

Module - Systems of Equations
Introduction - Tweedledum and Tweedledee

 Lessons 1- Graphing Systems of Equations 2- Solving Systems by Substitution 3- Solving Systems by Elimination Using Addition and Subtraction 4- Solving Systems by Elimination Using Multiplication 5- Solving Systems of Inequalities by Graphing 6- Module Review

Charles Dodgson, better known as Lewis Carroll, was an English mathematician who incorporated math and science into his children’s tales. He is the author of Alice in Wonderland and Through the Looking Glass. Consider the passage from the latter book. "Tweedledum said to Tweedledee: ‘The sum of your weight and twice mine is 361 pounds.’ Tweedledee said to Tweedledum: ‘Contrariwise, the sum of your weight and twice mine is 362 pounds.’ " In this unit, we will solve this problem using the two equations:

 x + 2y = 361 2x + y = 362

where x = Tweedledee’s weight and y = Tweedledum’s weight. In this problem, the solution is: Tweedledum is 120 lbs, Tweedledee is 121 lbs.

Upon completion of the activities in this unit, you should be able to:
• Use the following terms in a written paragraph to describe the key concepts of this unit.
• substitution
• system of equations
• elimination
• system of inequalities
• Solve systems by graphing.
• Determine whether a system has 1 solution, no solutions, or infinitely many solutions.
• Solve systems by the substitution method.
• Solve systems by the elimination method using addition, subtraction, and multiplication.
 HCPS 2002-