Section 1 of 8

Learning Outcomes

Use letters to represent unknown numbers, generalised numbers and variables
Evaluate algebraic expressions by substituting given values
Add and subtract linear expressions by combining like terms
Expand linear expressions using the distributive law
Factorise linear expressions by extracting common factors
Simplify algebraic expressions with fractional coefficients

Contents▾

Why Algebra Matters 4.1Basic Algebraic Concepts and Notations 4.2Evaluating Algebraic Expressions 4.3Addition and Subtraction of Linear Expressions 4.4Expansion: The Distributive Law 4.5Factorisation 4.6Algebraic Fractions Chapter Summary

Why Algebra Matters

Think of any two-digit number above 20, add its digits, and subtract that sum from the number you started with. The answer is a multiple of $9$ , every time.

Why? With tens digit $a$ and units digit $b$ the number is $10a + b$ , and $(10a + b) - (a + b) = 9a$ . Algebra turns "it always works" into a reason.

Practise this

Questions on Basic Algebra and Algebraic Manipulation, marked as you go, with the working shown.

Practise Basic Algebra and Algebraic Manipulation