Mathematics·Algebra · NSSCO 6.5
Formulae & changing the subject
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A formula is just a recipe written in letters, and this lesson makes it feel friendly. We start by seeing what a formula is and building one straight from a word description. Then we substitute numbers in carefully — minding negatives, powers and roots. After that comes the big skill: changing the subject. We rearrange formulae one step, two steps, with brackets and fractions, then the sneaky case where the new subject appears twice and we factorise it out, and finally formulae with a square or a square root.
What you'll learn in this lesson
By the end you should be able to (NSSCO Mathematics 6.5):
- Understand what a formula is and identify its subject
- Construct a formula from a word description
- Substitute numbers into a formula, including negatives, powers and roots, following BODMAS
- Change the subject of a simple formula using one and two inverse operations
- Change the subject of formulae involving brackets and fractions
- Change the subject when the new subject appears twice by factorising it out
- Change the subject where a square or a square root is involved
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