Réponse :
Explications étape par étape
A = (5x - 3)² - (5x - 3)(2x + 1)
1) A = (5x - 3)² - (5x - 3)(2x + 1)
A = 25x² - 30x + 9 - ( 10x² + 5x -6x - 3)
A = 25x² - 30x + 9 - 10x² - 5x + 6x + 3
A = 15x² - 29x + 12
2) A = (5x - 3)² - (5x - 3)(2x + 1)
A = (5x - 3) [(5x - 3) - (2x + 1)]
A = (5x - 3)(5x - 3 - 2x - 1)
A = (5x - 3)(3x - 4)
3) A = (5x - 3)(3x - 4) = 0
soit 5x - 3 = 0 5x = 3 x = 3/5
soit 3x - 4 = 0 3x = 4 x = 4/3
S = { 3/5 ; 4/3 }
