Réponse :
bonsoir
a + b = 11 et a - b = 4
a + b = 11 ⇔ a = 11 - b
a - b = 4 ⇔ 11 - b - b = 4 ⇔ - 2 b = 4 - 11 = - 7 ⇔ b = 3.5
a + 3.5 = 11 ⇔ a = 11 - 3.5 = 7.5
a = 7.5 et b = 3.5
a² = 7.5² = 56.25
b ² = 3.5² = 12.25
a - b = 4
a² - b ² = 56.25 - 12.25 = 44
44 = 4 x 11
conjecture ( a + b ) ( a - b) = a² - b ²
Explications étape par étape
