Bonjour !
7)
[tex](4x - 9)x \\ = 4 {x}^{2} - 9x[/tex]
8)
[tex]2x - ( - 5x + 4) \\ = 2x + 5x - 4 \\ = 7x - 4[/tex]
9)
[tex] {(6x - 2)}^{2} + 3x \\ = 36 {x}^{2} - 24x +4 + 3x \\ = 36 {x}^{2} - 21x + 4[/tex]
10)
[tex](4x - 1)( - 2x - 1) \\ = - 8 { {x}^{2} } - 4x + 2x + 1 \\ = - 8 {x}^{2} - 2x + 1[/tex]
11)
[tex](x - 3)(x + 3) \\ = {x}^{2} - 9[/tex]
12)
[tex](x - 1)6x \\ = 6 {x}^{2} - 6 x[/tex]
13)
[tex](6x - 2)7 + 4x(3x + 1) \\ = 42x - 14 + 12 {x}^{2} + 4x \\ = 12 {x}^{2} + 46x - 14[/tex]
14)
[tex]( - 10x - 7) {}^{2} \\ = 100 {x}^{2} + 140x + 49[/tex]
Bonne journée
