Explications étape par étape:
1. A =(3x + 2)(5x - 3)- (5x - 3)²
= 15x² - 9x + 10x - 6 - ( 25x² - 30x + 9 )
= 15x² + x - 6 - 25x² + 30x - 9
= -10x² + 31x - 15
2. A= (3x + 2)(5x - 3) - (5x - 3 )²
= (5x - 3) ( 3x + 2 - 5x + 3 )
= (5x - 3) ( -2x + 5 )
3. A= -10x² + 31x -15
= -10 × (-1)² + 31 ×(-1) - 15
= -10 - 31 - 15
= - 56
