Bonjour !
[tex]A=(3x - 2)(2x + 8) - (3 - 5x)( - 2x + 8) \\ = 6 {x}^{2} + 20x - 16 - (10 {x}^{2} - 46x + 24) \\ = 6 {x}^{2} + 20x - 16 - 10 {x}^{2} + 46x - 24 \\ = - 4 {x}^{2} + 66x - 40[/tex]
[tex]B=(x + 1)(x + 2) - 5(x + 2) \\ = {x}^{2} + 3x + 2 -5x - 10 \\ = {x}^{2} - 2x - 8[/tex]
[tex]C=(2x + 1)(2x + 1)(2x - 4)(x + 3) \\ = {(2x + 1)}^{2} (2x - 4)(x + 3) \\ = (4 {x}^{2} + 4x + 1)(2 {x}^{2} + 2x - 12) \\ = 8 {x}^{4} + 8 {x}^{3} - 48 {x}^{2} + 8 {x}^{3} + 8 {x}^{2} - 48x + 2 {x}^{2} + 2x - 12 \\ = 8 {x}^{4 } + 16 {x}^{3} - 38 {x}^{2} - 46x - 12[/tex]
Bonne journée
