Bonjour !
a)
[tex](x + 5)(x + 3) \\ = {x}^{2} + 3x + 5x + 15 \\ = {x}^{2} + 8x + 15[/tex]
b)
[tex] (3x + 2)(x+4) \\ = 3 {x}^{2} + 12x + 2x + 8 \\ = 3 {x}^{2} + 14x + 8[/tex]
c)
[tex](x+3)(x - 2) \\ = {x}^{2} - 2x + 3x - 6 \\ = {x}^{2} + x - 6[/tex]
d)
[tex](x-4)(x - 1) \\ = {x}^{2} - x - 4x + 4 \\ = {x}^{2} - 5x = 4[/tex]
Bonne soirée