Réponse:
[tex]a = 5(3y + 12) \\ = 5 \times 3y + 5 \times 12 \\ = 15y + 60[/tex]
[tex]b = 8x(3 + 7x) \\ = 8x \times 3 + 8x \times 7x \\ = 24x + 56 {x}^{2} [/tex]
[tex]c = (9x + 2)(18 + 4x) \\ = 9x \times 18 + 9x \times 4x + 2 \times 18 + 2 \times 4x \\ = 162x + 36 {x}^{2} + 36 + 8x \\ = 36 {x}^{2} + 170x + 36[/tex]
