Répondre :
1)
a) A₁ = ((x+3)(x+3))/2
b) A₂ = 2(x+3)
2)
a) 2 × A₁ - 2 × A₂ = 2 × ((x+3)(x+3))/2 - 2 × 2(x+3)
= (x+3)(x+3) - 4(x+3)
= (x+3)[(x+3)-4]
= (x+3)(x-1)
b) aire ABCD = aire CDE
⇒ ((x+3)(x+3))/2 = 2(x+3)
⇒ (x+3)(x+3) = 4(x+3)
⇒ (x+3)(x+3) - 4(x+3) = 0
⇒ (x+3)(x-1) = 0
⇒ x+3 = 0 ou x-1 = 0
⇒ x = -3 ou x = 1