Formulae — O/L Mathematics

What must I remember about Formulae?

• Mathematical Formula: An equation expressing a mathematical or physical relationship between two or more variables (e.g., v = u + at, A = πr²).
• Subject of a Formula: The single variable isolated on one side of the equals sign with a coefficient of exactly +1 (e.g., in y = mx + c, y is the subject).
• Changing the Subject: Process of rearranging algebraic terms using inverse operations (addition/subtraction, multiplication/division, squaring/square root) to isolate a different specified variable.
• Linear vs Non-linear Isolation: When the target variable appears in multiple terms, collect all terms containing the target variable on one side and factorize out the common variable.

Test yourself (1 minute)

1. Clearing fractions first

   When a formula contains fractions, multiply every term on both sides by the Lowest Common Multiple (LCM) of all denominators before rearranging.

2. Target variable under radical/fraction

   If target variable x is under a square root (e.g., T = 2π√(L/g)), isolate radical first, then square both sides: T² = 4π²(L/g) => g = (4π²L) / T².

3. Target variable in denominator

   Cross-multiply to bring the target variable to the numerator; NEVER leave the isolated subject in the denominator.

Practise Formulae questions today

Source: NIE G.C.E. (O/L) Mathematics Syllabus (Grade 10, Unit 22)

What should I study first?

What comes next?

Next in the syllabus

Where does Formulae fit in the syllabus?

Grade 10 · Term 3