Bonjour,
A = 7x - 3x (2 - 5x)
= 7x - 6x + 15x²
= 15x² - x
B = (5x - 3)²
= (5x)² - 2×5x×3 + 3²
= 25x² - 30x + 9
C = (2x + 1)(4x + 5)
= 8x² + 10x + 4x + 5
= 8x² + 14x + 5
D = 5(7 - 6x) + (3x + 2)(x -3)
= 35 - 30x + 3x² - 9x + 2x - 6
= 3x² - 37x + 29
E = (x + 2)² - (2x - 3)(x+1)
= x² + 2×x×2 + 2² - (2x² + 2x - 3x - 3)
= x² + 4x + 4 - 2x² - 2x + 3x + 3
= -x² + 5x + 7
Bonne soirée ^^
