Year 9 - Maths
Changing the subject to suit the context
Expressions and formulae
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This pupil-friendly study guide includes a unit summary, clear notes, common mistakes, and quick questions with answers.
Unit Summary
This unit develops pupil understanding of formulae and how to rearrange them. Pupils will learn how to recognise and manipulate binomials and learn to recognise the difference of two squares.
Lesson Summary
You will learn to evaluate different problems to ascertain when rearranging a formula is beneficial.
Key Notes
- Formulae are used in a variety of places, such as the science lab but also in factories.
- Rearranging the formula may be beneficial when what you wish to calculate is not the subject.
- You can compare rearranging the formula to solving for one unknown.
Vocabulary To Learn
- Subject of an equation/formula: The subject of an equation/a formula is a variable that is expressed in terms of other variables. It should have an exponent of 1 and a coefficient of 1.
Common Mistakes To Avoid
- That the gradient of a line given the equation of the line is always just the coefficient of the x term.
3 Quick Questions (With Answers)
1. Solve this in steps: explain the method from this lesson and why each step matters.
Formulae are used in a variety of places, such as the science lab but also in factories. Rearranging the formula may be beneficial when what you wish to calculate is not the subject.
2. Use this key word in a maths sentence and explain it clearly. 'Subject of an equation/formula'
The subject of an equation/a formula is a variable that is expressed in terms of other variables. It should have an exponent of 1 and a coefficient of 1. Use this word when showing your method, then check your final answer is reasonable.
3. Spot and fix this common maths mistake.
Mistake: That the gradient of a line given the equation of the line is always just the coefficient of the x term. Correction: Using graphing software to explore this could help.
More Lessons In This Unit
- Additive relationships Study Guide
- Changing the subject with more complex formula Study Guide
- Changing the subject with simple formula Study Guide
- Checking and securing solving linear equations Study Guide
- Checking and securing understanding of the distributive law with algebraic terms Study Guide
- Difference of two squares Study Guide
- Evaluating expressions with and without changing the subject Study Guide
- More complex binomial products Study Guide
- Multiplicative relationships between terms Study Guide
- Problem solving with expressions and formulae Study Guide
- The product of two binomials Study Guide
Browse all guides in the Year 9 Maths guide library.