svp aidez moi merci ​

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 !!!