exercice 56:

b. 5x(4-x)=0

c.(x+3)²=0

exercice 58 :

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

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

exercice 61 :

a.x²-4=0

b.x²-6x+9=0

exercice 62 :

a.4x²-1=0

b.(x-3)²-4=0​