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Henrico County Public Schools, Virginia
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Module - Systems of Equations
Introduction - Tweedledum and Tweedledee



Graphing Systems of Equations


Solving Systems by Substitution


Solving Systems by Elimination Using Addition and Subtraction


Solving Systems by Elimination Using Multiplication


Solving Systems of Inequalities by Graphing


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-