Réponse:
[tex]a = 3(x + 5) \\ = 3x + 3 \times 5 = 3x + 15 \\ b = 3 - (x + 5) \\ = 3 - x - 5 = - x - 2 \\ c = 2x(3 - x) \\ = 2x \times 3 - 2x \times x \\ = 6x - 2 {x}^{2} \\ d = - 5(4x - 1) \\ = - 5 \times 4x - 5 \times - 1 \\ = - 20x + 5 \\ e = 3x + 5x(x - 2) \\ 3x + 5x \times x + 5x \times - 2 \\ = 3x + 5 {x}^{2} - 10x \\ = 5 {x}^{2} - 7x \\ f = 4x(x - 3) - (x + 1) - {x}^{2} \\ = 4x \times x + 4x \times ( - 3) - x - 1 - {x}^{2} \\ = 4 {x}^{2} - 12x - x - 1 - {x}^{2} \\ = 3 {x}^{2} - 13x - 1[/tex]
