Substitution

Substitution means replacing each pronumeral with its value and then working out the result. In NSW Year 8 maths the values are often negative, so each one goes in brackets before the order of operations is applied (NESA outcome MA4‑ALG‑C‑01).

You will find the value of expressions such as \(2x - 3y\) when \(x = 2\) and \(y = -2\), work with powers of negatives in \(2x^2 - 3y^2\), and evaluate fractions by working out the whole top and the whole bottom first. You will also test which expression gives a stated value. Freezer temperatures, bank balances in the red and a diver's depth all call for substituting negative numbers. It is part of Year 8 Algebra.