Bonjour,
Exercice 2 :
a. 25 = 5²
b. 4x² = (2x)²
c. 36 - 25x² = 6² - (5x)²
Exercice 3 :
d. (k + 6)(k - 6) = k² - 36
e. (1 - 7x)(1 + 7x) = 1 - 49x²
f. (10y + 3)(10y - 3) = 100y² - 9
g. 36 - 25x² = (6 - 5x)(6 + 5x)
h. (2 - x)(2 + x) = 4 - x²
i. (5x + 1)² - 9
= (5x + 1)² - (3)²
= (5x + 1 - 3)(5x + 1 + 3)
= (5x - 2)(5x + 4)
Pour rappel,
(a - b)(a + b) = a² - b².
