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Year 10 - Maths

Solving a quadratic and linear pair of simultaneous equations using substitution

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 solve two (one linear, one quadratic) simultaneous equations algebraically using substitution.

Key Notes

  • Consider which variable to make the subject for the substitution.
  • Depending which variable you chose, you may need to expand a pair of bracketed expressions.
  • Your choice may make the substitution significantly easier.

Vocabulary To Learn

  • Substitution: Substitute means to put in place of another. In algebra, substitution can be used to replace variables with values, terms, or expressions.

Common Mistakes To Avoid

  • Pupils find the two $$x$$ values after solving the combined quadratic and declare that the solution.

3 Quick Questions (With Answers)

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

Consider which variable to make the subject for the substitution. Depending which variable you chose, you may need to expand a pair of bracketed expressions.

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

Substitute means to put in place of another. In algebra, substitution can be used to replace variables with values, terms, or expressions. Use this word when showing your method, then check your final answer is reasonable.

3. Spot and fix this common maths mistake.

Mistake: Pupils find the two $$x$$ values after solving the combined quadratic and declare that the solution. Correction: It is important to substitute both $$x$$ values back in to one of the original equations to find the corresponding $$y$$ values. Without these, the solutions are incomplete.

More Lessons In This Unit

Browse all guides in the Year 10 Maths guide library.