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Bonjour,

Voici en pièce jointe l'exercice.

Bonjour,

A = (3x + 8)(4 + 5x)

A = 3x × 4 + 3x × 5x + 8 × 4 + 8 × 5x

A = 12x + 15x² + 32 + 40x

A = 12x + 40x + 15x² + 32

A = 52x + 15x² + 32

B = (11 + x)(4 + 9x)

B = 11 × 4 + 11 × 9x + x × 4 + x × 9x

B = 44 + 99x + 4x + 9x²

B = 99x + 4x + 9x² + 44

B = 103x + 9x² + 44

C = (6 + 12x)(x + 2)

C = 6 × x + 6 × 2 + 12x × x + 12x × 2

C = 6x + 12 + 12x² + 24x

C = 6x + 24x + 12² + 12

C = 30x + 12x² + 12

En espérant avoir pu t'aider :)