A mathematical proof is a sequence of statements that follow on logically from each other that shows that something is always true. Using letters to stand for numbers means that we can make statements ...

To expand a bracket means to multiply each term in the bracket by the expression outside the bracket. For example, in the expression \(3(m + 7)\), multiply both \(m\) and 7 by 3, so: \(3(m + 7) = 3 ...