bjr
(a-b)² = a² - 2ab + b²
ici
on a (11 - b)² = 121 - 2*11*b + x² => b² = x² => b = x
=> (11 - x)² = 121 - 22x + x²
le b
(a+b)² = a² + 2ab + b²
donc (a + 2x)² = 25 + 2ab + b²
comme a² = 25 => (5 + 2x)² = 25 + 20x + 4x²
le c
(a-b)² = a² - 2ab + b²
ici a² = 4x² => a = 2x et b² = 9 = b = 3 => (2x - 3)² = 4x² - 12x + 9
et
le d
(a-b) (a+b) = a² - b²
ici b² = 100x² => b = 10x
(7 - 10x) (7+10) = 49 - 100x²
