a) l'ensemble de définition de A(x) et P(x) est x ∈ [0 ; 6]
b) A(x) = (6 + x)(6 + x) = (6 + x)²
P(x) = 4* (6 + x)
c) Calculer P(x) lorsque A(x) = 51.84
A(x) = (6 + x)² = 51.84 ⇒ (6 + x) = √51.84
P(x) = 4 * (6 + x) = 4 * √51.84 = 28.8 ≈ 29 cm
d) calculer A(x) lorsque P(x) = 32.8
P(x) = 4 * (6 +x) = 32.8 ⇒ (6 +x) = 32.8/4 = 8.2 cm
A(x) = (6 + x)(6 +x) = 32.8/4 * 32.8/4 = 8.2 * 8.2 = 67.24 cm²
