Author note — to cover

Substitute negative values wrapped in brackets, covering (−3)² versus −3², subtracting a negative, and products of two negatives, in expressions like 2x² − 3x with x = −4. Boundaries: positive-only substitution and formula work sit on the sibling pages; the sign conventions themselves are Number-strand material. Both tiers. (A2)

Introduction

—coming soon—

Practice and continue

Practice

Substituting negative numbers

Substituting a negative value with brackets, so the sign survives squaring.

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Substituting into terms with powers

Why 3x² means square first then multiply by 3, so x = 4 gives 48 not 144.