Write using indices.
Algebra · notation and manipulation
Notes and three levels of exam-style practice for each registered specification point in this section.
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Use and interpret algebraic manipulation: ab for a × b, 3y for y + y + y and 3 × y, a² for a × a, a³ for a × a × a, a²b for a × a × b, a/b for a ÷ b, coefficients as fractions, brackets
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Explanation
- Algebraic notation records operations compactly. Adjacent letters mean multiplication, so , while means three lots of .
- An index records repeated factors: and .
- A fraction bar represents division and also groups its numerator and denominator.
- Write numerical coefficients before variables, usually as exact fractions rather than decimals, and use brackets when an operation acts on a complete expression.
- Examiners expect conventional notation and the operations to remain unambiguous when translating words or repeated products.
Worked example
A rectangle has length and width . Write its area and perimeter in conventional algebraic notation.
- 1.Area .
- 2.Perimeter .
- 3.Simplify to .
Answer: Area and perimeter .
Common mistakes
- Don't read as instead of .
- Don't interpret as rather than .
- Don't drop brackets when a multiplier must act on a whole expression.
Exam tip
Translate one operation at a time and use brackets before simplifying the notation.
Tier 1 · Easy
Tier 2 · Standard
Write in conventional algebraic notation, and state its coefficient.
Tier 3 · Hard
A rectangle has length and width . Write its area and its perimeter in conventional algebraic notation.
Substitute numerical values into formulae and expressions, including scientific formulae
The Secure button is a self-rating. Evidence-secure needs the latest Tier 2/3 attempt correct, plus three correct distinct drills across at least two dates and two practice sources.
Explanation
- Substitution replaces every occurrence of a variable with its given value while preserving the original operations. Put negative and fractional values in brackets so that powers and signs act on the whole value.
- Follow the order of operations: evaluate powers before multiplication, division, addition and subtraction.
- In a scientific formula, include the stated units and convert them first if necessary.
- Keep full calculator precision until the requested rounding.
- Examiners award method for a correct substituted expression, so write that line before evaluating rather than giving only a calculator answer.
Worked example
The kinetic energy formula is . Find when and .
- 1.Substitute both values: .
- 2.Evaluate the power first: .
- 3..
Answer: .
Common mistakes
- Don't substitute into as .
- Don't write as after omitting the brackets.
- Don't round an intermediate value and loses accuracy in the final answer.
Exam tip
Show the formula with every value substituted before entering it into the calculator.
Tier 1 · Easy
Work out when .
Tier 2 · Standard
The kinetic energy of an object is given by . Work out when and .
Tier 3 · Hard
Use to calculate when and . Give your answer in standard form.
Understand and use the concepts and vocabulary of expressions, equations, formulae, identities, inequalities, terms and factors
The Secure button is a self-rating. Evidence-secure needs the latest Tier 2/3 attempt correct, plus three correct distinct drills across at least two dates and two practice sources.
Explanation
- An expression has no equality or inequality sign. An equation is true only for particular values, whereas an identity is true for every permitted value and is written with .
- A formula links quantities, and an inequality compares a range of possible values.
- Terms are separated by addition or subtraction; factors are quantities multiplied together.
- For example, has two terms and factorises as , whose factors are and .
- Examiners expect the correct vocabulary and a reason based on the statement's structure or truth.
Worked example
Classify , , and .
- 1. is true only for a particular value, so it is an equation.
- 2.Expanding always gives , so the second statement is an identity.
- 3.The symbol compares possible values, so the third statement is an inequality.
Answer: Equation, identity, inequality, in that order.
Common mistakes
- Don't call every statement containing an equals sign an identity.
- Don't count factors as terms even though terms are separated by addition or subtraction.
- Don't use instead of for a relationship true for all permitted values.
Exam tip
When asked to classify a statement, justify whether it is always true, sometimes true or a comparison.
Tier 1 · Easy
State whether is an expression, equation or inequality.
Tier 2 · Standard
For , state the number of terms on the left and name the two factors on the right.
Tier 3 · Hard
Classify each statement as an equation, an identity or an inequality: , , and .
Simplify and manipulate algebraic expressions (incl. surds and algebraic fractions): like terms, common factors, expanding two or more binomials, factorising quadratics incl. ax² + bx + c, indices
The Secure button is a self-rating. Evidence-secure needs the latest Tier 2/3 attempt correct, plus three correct distinct drills across at least two dates and two practice sources.
Explanation
- Simplify by collecting only like terms and applying index laws only to matching bases. Expand brackets by multiplying every required pair of terms, then collect.
- When factorising, first remove any common factor and check that re-expansion reproduces every term.
- Foundation questions can include expanding two binomials and factorising .
- Higher tier: manipulation extends to surds, algebraic fractions, products of more binomials and quadratics .
- Never cancel terms across addition; factorise complete numerators and denominators first, then retain values excluded by the original denominator.
Worked example
Factorise fully.
- 1.Find two numbers with product and sum : and .
- 2.Write the factors .
- 3.Check by expanding: .
Answer: .
Common mistakes
- Don't collect unlike terms such as to make .
- Don't miss a cross-term when expanding two brackets.
- Don't cancel terms across addition in an algebraic fraction.
Exam tip
After factorising, expand your answer mentally; it must reproduce the original expression exactly.
Tier 1 · Easy
Simplify .
Tier 2 · Standard
Factorise .
Tier 3 · Hard
Simplify , stating every value of excluded from the original expression.
Understand and use standard mathematical formulae; rearrange formulae to change the subject
The Secure button is a self-rating. Evidence-secure needs the latest Tier 2/3 attempt correct, plus three correct distinct drills across at least two dates and two practice sources.
Explanation
- The subject of a formula is the variable isolated on one side. Changing the subject must preserve an equivalent relationship, so perform the same operation on both sides and undo operations in reverse order.
- Clear fractions or brackets when this makes the structure easier to see.
- Foundation questions usually isolate a subject that appears once.
- Higher tier: the subject may appear more than once or inside a fraction, requiring expansion and collection of its terms.
- Examiners expect each inverse operation to be visible and the final subject to appear alone.
Worked example
Make the subject of .
- 1.Subtract from both sides: .
- 2.Divide both sides by : .
- 3.Write the subject first: .
Answer: .
Common mistakes
- Don't change a sign while moving a term without applying an operation to both sides.
- Don't divide only one term of a sum instead of the entire side.
- Don't stop with the requested subject still multiplied by another quantity.
Exam tip
State one balancing operation per line until the requested subject is alone.
Tier 1 · Easy
Make the subject of .
Tier 2 · Standard
The area of a trapezium is given by , where is measured in and , and are measured in cm. (a) Make the subject of the formula. (b) Hence work out when , and .
Tier 3 · Hard
Make the subject of .
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