Exercice 74 aider moi s'il vous plait!

Bonjour,

A = 3 (5x - 2) + (x + 1) (5x - 2)
A = 15x - 6 + 5x² - 2x + 5x - 2
A = 5x² + 15x + 5x - 2x - 6 - 2
A = 5x² + 18x - 8

B = (2x- 3) (x + 2) - 5 (2x - 3)
B = 2x² + 4x - 3x - 6 - 10x + 15
B = 2x² + 4x - 3x - 10x - 6 + 15
B = 2x² - 9x + 9

C = 9x² - 4 - (3x - 2) (x - 3)
C = 9x² - 4 - (3x² - 9x - 2x + 6)
C = 9x² - 4 - 3x² + 9x + 2x - 6
C = 9x² - 3x² + 9x + 2x - 4 - 6
C = 6x² + 11x - 10