Réponse:
Bonjour,
Explications étape par étape:
Exercice 1:
1) (3x -7)(2x-8)
= 6x^2 - 24x -14x + 56
= 6x^2 -38x +56
2) (-5x -9)(3-4x)
= -15x +20x^2 -27 +36x
=21x+20x^2 -27
= 20x^2 +21 -27
2)
Pour x=6
(3*6 -7)(2*6 -8)
=(18-7)*(12-8)
=11*4
=44
Pour x=6
(-5*6-9)(3-4*6)
=(-30-9)*(3-24)
= -39*(-21)
= 819
3)
C= 32x +80
= 16(2x +5)
F= 28x^2 -21x
=7x(4x-3)
Exercice 2
A) (2x+9)(3x-10)+(4x+5)(-3x-6)
= 6x^2-20+27x-90-12x^2-24x -15x-30
= -6x^2-32x-90-30
= -6x^2-32x-120
B) (4x+5)(3x+4)-(2x-7)(-6x+4)
=12x^2 +16x+15+20-(-12x^2+8x+42x-28)
= 12x^2+16x+15x+20+12x^2-50x+28
= 24x^2-19x+48
C) (2x+3)(5x-7)+(3x-4)(2x+3)
=(2x+3)(5x-7+3x-4)
=(2x+3)(8x-11)
D) (4x-5)(x+8)-(x+8)(2x-4)
=(x+8)*[4x-5-(2x-4)]
=(x+8)*(2x-5+4)
=(x+8)*(2x-1)
Exercice 4:
A) 6/7+3/7 * 5/4+9/4
=6/7+15/28+9/4
=51/41
(~3.642857143)
B) 1/5+1/4*3/5-12/7
=1/5+3/20-12/7
=-191/140
(~1.364285714)
Voilà tous les calculs !!!
