Solving Simultaneous Equations

Students learn how to set up and solve a pair of simultaneous equations using the elimination method.  Learning progresses from solving equations where the coefficients are equal to setting up a pair of equations with different coefficients from known facts.

This unit takes place in Term 2 of Year 11 and follows on from solving equations with a single unknown.


Solving Simultaneous Equations Lessons
Revision Lessons

Prerequisite Knowledge

  • Solve two simultaneous equations in two variables algebraically;
  • Find approximate solutions to simultaneous equations in two variables using a graph
  • Translate simple situations or procedures into algebraic expressions or formulae; derive an equation

Success Criteria

  • Solve two simultaneous equations in two variables algebraically;
  • Find approximate solutions using a graph

Key Concepts

  • For every unknown an equation is needed.
  • Students need to have a secure understanding of adding and subtracting with negatives when eliminating an unknown.
  • Coefficients need to be equal in magnitude to eliminate an unknown.
  • Students need to check their solutions by substituting the calculated values into the original equations.

Common Misconceptions

  • Students often struggle knowing when to add or subtract the equations to eliminate the unknown. Review addition with negatives to address this.
  • Equations need to be aligned so that unknowns can be easily added or subtracted. If equations are not aligned students may add or subtract with non like variables.
  • Students often try to eliminate variables with their coefficients being equal

Mr Mathematics Blog

Multiplication and Division Rule of Indices

Using the rules of indices students learn how to evaluate expressions in index notation.

Problem Solving Maths Lessons

Four new problem solving lessons to develop student’s mathematical reasoning and communication skills.

Enlarging Shapes by a Negative Scale Factor

How to teach performing and describing negative scale factor enlargements.