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

Leave a Reply

Your email address will not be published. Required fields are marked *

You may use these HTML tags and attributes:

<a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <s> <strike> <strong>

This site uses Akismet to reduce spam. Learn how your comment data is processed.

Mr Mathematics Blog

Deep Dive Mathematics Inspection

My experience as a Head of Mathematics going through the deep dive OFSTED inspection.

Calculating a Reverse Percentage

How to use ratios and proportional reasoning as a model for finding the original amount after a percentage change.

Area of Compound Shapes

To find the area of compound shapes students need to understand what the word compound means.