Salut ! :)
a) (x + 5)² = x² + 2×x×5 + 5² = x² + 10x + 25
b) x² - 12x + 36 = x² - 2×x×6 + 6² = (x - 6)²
c) 4x² + 40x + 100 = (2x)² + 2×2x×10 + 10² = (2x + 10)²
d) (x + 10)(x - 10) = x² - 10² = x² - 100
e) x² - 121 = x² - 11² = (x + 11)(x - 11)
f) 49x² - 14x + 1 = (7x)² - 2×7x×1 + 1² = (7x - 1)²
Voilà, j'espère que tu as compris. :)
