cosigne développer puis réduire les expressions suivants

45)
A = (x + 3) (4 + x)
A = 4x + x² + 12 + 3x
A = x² + 7x + 12

B = (y - 5) (y + 2)
B = y² + 2y - 5y - 10
B = y² - 3y - 10

46)
A = (a - 7) (6 - a)
A = 6a - a² - 42 + 7a
A = - a² + 13a - 42

B = (x + 7) (x - 1)
B = x² - x + 7x - 7
B = x² + 6x - 7

47)
A = (8b - 1) (- b - 4)
A = - 8b² - 32b + b + 4
A = - 8b² - 31b + 4

B = (7 - 5x) (2 - x)
B = 14 - 7x - 10x + 5x²
B = 5x² - 17x + 14

48)
A = (3x + 1) (5x + 4)
A = 15x² + 12x + 5x + 4
A = 15x² + 17x + 4

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

49)
A = (7x - 1) (2y - 8)
A = 14xy - 56x - 2y + 8

B = (- 7 - 2a) (- 4 - 5b)
B = 28 + 35b + 8a + 10ab
B = 10ab + 8a + 35b + 28

50)
A = (- 1 - 9x) (1 + 9x)
A = - 1 - 9x - 9x - 81x²
A = 81x² - 18x - 1

B = (- 3x - 5) (1 - 4x)
B = - 3x + 12x² - 5 + 20x
B = 12x² + 17x - 5

C = (- x + 3) (2 - x)
C = - 2x + x² + 6 - 3x
C = x² - 5x + 6

51)
A = (7x - 2) (3 - x) - 2x + 4
A = 21x - 7x² - 6 + 2x - 2x + 4
A = - 7x² + 21x - 2

B = (2 - 3x) (4 + 5) - 5x² + 2x - 1
B = 8 + 10 - 12x - 15x - 5x² + 2x - 1
B = - 5x² - 25x + 17

52)
A = (x - 1) (7 - x) + 3 (4x² - 2x - 3)
A = 7x - x² - 7 + x + 12x² - 6x - 9
A = 11x² + 2x - 16

B = (3 - 4x) (5x - 6) - 4 (2x² - 7x + 1)
B = 15x - 18 - 20x² + 24x - 8x² + 28x - 4
B = - 28x² + 67x - 22