Salut ´

a) 2x(4x-5) = 0

2x = 0 => x= -2

(4x-5) = 0 => x= 4/5

b) (3-2n)(n+4) = 0

(3-2n) = 0 => n = 3/2

(n+4) = 0 => x = -4

Bon courage

(x+3)(x+3) = 0

(x+3) = 0 => x= -3

(x+3) = 0 => x = -3

Bon courage.