☺ Salut ☺
Factorisons [tex]A = 3x + 21[/tex] par [tex]3[/tex] :
[tex]\boxed{A = 3x + 21 = 3 \times \red{x} + 3 \times \red{7}}[/tex]
ou encore :
[tex]\boxed{A = 3x + 21 = 3 \times (\green{x} + \green{7})}[/tex]
[tex]\boxed{\blue{\boxed{A = 3x + 21 = 3(\green{x} + \green{7})}}}[/tex]
