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 ^^