Bonjour

15)

a. (x - 1) (2x + 5)

= 2x² + 5x - 2x - 5

= 2x² + 3x - 5

b. (4 - 2x) (5x - 9)

= 20x - 36 - 10x² + 18x

= - 10x² + 20x + 18x - 36

= - 10x² + 38x - 36

c. (- x + 1) (x - 1)

= - x² + x + x - 1

= - x² + 2x - 1

d. (- 3 - 2x) (- 6 - 3x)

= 18 + 9x + 12x + 6x²

= 6x² + 21x + 18

16)

a. 4 - 2x (3x + 5)

= 4 - 6x² - 10x

= - 6x² - 10x + 4

b. (- 4 * 3x) (x  * 9)

= - 12x * 9x

= - 108x²

c. (3x + 9)²

= 9x² + 54x + 81

d. (7x - 8) (4x - 6) + 10

= 28x² - 42x - 32x + 48 + 10

= 28x² - 74x + 58.