Réponse:
1.
[tex] 2x \times ( - x) + 2x + 5 + ( - 6) \times ( - x) + ( - 6) \times 5 \\ = - 2x ^{2} + 10x + 6x - 30 \\ = - 2x ^{2} + 16x - 30[/tex]
2.
[tex]3x \times x + 3x \times ( - 8) \\ = 3x ^{2} - 24x[/tex]
3.
[tex]2 \times x + 2 \times 5 - 3x - 5 \\ = 2x + 10 - 3x + 5 \\ = 2x - 3x + 10 + 5 \\ = - x + 5[/tex]
4.
[tex]4x + 5 - ( - 5x) \times x \\ = 4x + 5 + 5x \times x + 5x \times - 9 \times x - 9 \times 1 \\ = 4x + 5 + 5x ^{2} + 5x - x - 9 \\ = 5x ^{2} + 4x + 5x - 9x + 5 - 9 \\ = {5x}^{2} + 9x - 9x + 5 - 9 \\ = 5x ^{2} - 4[/tex]
