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Year 10 - Maths

Combining equations

Simultaneous equations: 2 variables

Unit Summary

In this unit pupils will learn to solve a pair of simultaneous equations from different starting points and cases using a variety of strategies.

Lesson Summary

You will learn to additively combine two equations to create a third valid equation.

Key Notes

  • Two equations can be combined into a third equation.
  • You can combine equations using the standard arithmetic operations.
  • The new equation may not contain both variables any more.

Vocabulary To Learn

  • Elimination: Elimination is a technique to help solve equations simultaneously and is where one of the variables in a problem is removed.

Common Mistakes To Avoid

  • Mistakes can be made when subtracting negative values. E.g. thinking that 5 - - 2 = 3.

3 Quick Questions (With Answers)

1. Solve this in steps: explain the method from this lesson and why each step matters.

Two equations can be combined into a third equation. You can combine equations using the standard arithmetic operations.

2. Use this key word in a maths sentence and explain it clearly. 'Elimination'

Elimination is a technique to help solve equations simultaneously and is where one of the variables in a problem is removed. Use this word when showing your method, then check your final answer is reasonable.

3. Spot and fix this common maths mistake.

Mistake: Mistakes can be made when subtracting negative values. E.g. thinking that 5 - - 2 = 3. Correction: Consider additive inverses, subtracting a negative is the same as adding the additive inverse. Pupils should be able to spot mistakes in learning cycle 1 by checking their new equation is still true.

More Lessons In This Unit

Browse all guides in the Year 10 Maths guide library.