Bonjour,
1)
a. (x - 3/7) (7x - 14)
= 7x² - 14x - 21/7x + 42/7
= 7x² - 14x - 3x + 6
= 7x² - 17x + 6
b. (3 + 3/8x) (8 - x)
= 24 - 3x + 24/8x - 3/8x²
= - 3/8x² - 3x + 3x + 24
= - 3/8x² + 24.
2) Pour x = 0
7x² - 17x + 6
= 7 * 0² - 17 * 0 + 6
= 0
- 3/8x² + 24.
= - 3/8 * 0² + 24
= 24
Pour x = 1
7x² - 17x + 6
= 7 * 1² - 17 * 1 + 6
= 7 - 17 + 6
= - 4
- 3/8x² + 24
= - 3/8 * 1² + 24
= - 3/8 + 24
= - 3/8 + 192/8
= 189/8
