Bonjour aidez moi a l'exercice 23 :) il faut développer

23)

a) (x + 5) (x + 1)
= x² + x + 5x + 5
= x² + 6x + 5

b) (2x - 5) (x + 4)
= 2x² + 6x - 5x - 20
= 2x² + x - 20

c) (2x - 3) (3x - 8)
= 6x² - 16x - 9x + 24
= 6x² - 25x + 24

d) - (1 + 2x) (9x + 1)
= - (9x + 1 + 18x² + 2x)
= - 9x - 1 - 18x² - 2x
= - 18x² - 9x - 2x - 1
= - 18x² - 11x - 1

e) - (3x - 3/7) (7x - 14)
= - (21x² - 42x - 21/7x + 42/7)
= - 21x² + 42x + 21/7x - 42/7
= - 147/7x² + 294/7x + 21/7x - 42/7
= - 147x² + 294x + 21x - 42
= 147x² + 315x - 42

24)

A = 4x + (2x + 1) (5x - 3)
A = 4x + 10x² - 6x + 5x - 3
A = 10x² + 4x + 5x - 6x - 3
A = 10x² + 3x - 3

B = (x + 3) (y + 9) + 10x - 7
B = xy + 9x + 3y + 27 + 10x - 7
B = xy + 9x + 10x + 3y + 27 - 7
B = xy + 19x + 3y + 20

C = (3x - 5) (7 + 6x) - (7 + x)
C = 21x + 18x² - 35 - 30x - 7 - x
C = 18x² + 21x - 30x - x - 35 - 7
C = 18x² - 10x - 42