Bonjour,
4x² +9-8+7x²-9x+12
= 11x² -9x +13
5x(3x+3)-2x(6x-7)
= 15x² +15x -(12x² +14x)
= 15x² +15x -12x² -14x
= 3x²+x
choisis -9 ajoute 5 multiplie par 2 soustrais 5
-9
-9+5 = -4
-4*2 = -8
-8-5 = -13
(6x+3)(7x-3)
= 42x² -18x+21x -9
= 42x² +3x -9
5x+3=2x+6
5x-2x = 6 -3
3x= 3
3/3
=1
(3x+6)(4x-4)=0
Soit
3x+6 = 0
3x=-6
x= -6/3
x= -2
soit
4x-4 = 0
4x= 4
x= 4/4
x= 1
