Réponse:
[tex]a = 4x + 12 = 4(x + 3)[/tex]
[tex]b = 6x - 15 = 3(x - 5)[/tex]
[tex]c = 21x - 7x = 7x(3 - 1)[/tex]
[tex]d = 4 - 10x = 2(2 - 5x)[/tex]
[tex]e = 9 {x}^{2} + 6 = 3(3 {x}^{2} + 2)[/tex]
[tex]f = {x}^{2} - 4x = x(x - 4)[/tex]
[tex]g = 2x + 2 = 2(x + 1)[/tex]
[tex]h = {x}^{2} + x = x(x + 1)[/tex]
[tex]i = 4 {x}^{2} + 3 {x}^{2} = {x}^{2} (4 + 3)[/tex]
