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.
