Explications étape par étape:
[tex] - 2x(5x - 10) - (4x + 1)(2x + 3) = \\ - 10 {x}^{2} + 20x - (8 {x}^{2} + 12x + 2x + 3) = \\ - 10 {x}^{2} + 20x - (8 {x}^{2} + 14x + 3) = \\ - 10 {x}^{2} + 20x - 8 {x}^{2} - 14x - 3 = \\ - 10 {x}^{2} - 8 {x }^{2} + 20x - 14x - 3 = \\ - 18 {x}^{2} + 6x - 3 = \\ 3 \times ( - 6 {x}^{2} ) + 3 \times (2x) + 3 \times ( - 1) = \\ 3( - 6 {x}^{2} + 2x - 1)[/tex]
