help please c noté merci d'avance

bonjour,

1a) AH = AB-HB
            = 4-x

b)  A AHIJ = (4-x)²

A hachurée : (4-x)²-2²

2) (4-x)²-4 =
    16-8x+x²-4 = x²-8x+12

4) x²-8x+12
x =2
(2)² - (8*2)+12 =
4-16+12 = 0