Author note — to cover

Expand (x + a)(x + b) in all four sign combinations by grid or FOIL, collecting the two middle terms. Coefficients of x stay 1 here: (2x + 3)(3x − 1) is the sibling page, squaring a bracket its own page, and three brackets the Higher page. Both tiers. (A4)

Introduction

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Practice and continue

Practice

Expanding double brackets

Multiplying every term in one bracket by every term in the other.

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Double brackets with coefficients

Expanding (2x + 3)(3x − 1), keeping track of the middle terms.