q1
7x = 0 si x = 0 : 7 = 0
q2
7 (x-3) = 0 si x - 3 = 0 => x = 3
q3
a x b = 0
ou a = 0
ou b = 0
q4
donc (x-8) (2x-1) = 0
ou x - 8 = 0 => x = 8
ou 2x - 1 = 0 => x = 1/2
2 solutions
équation produit
