a)
cube bleu = a³
cube rose = b³
pavé orange = a × b²
pavé vert = a² × b
b) (a+b)³ = 1 cube bleu + 1 cube rose + 3 pavé vert + 3 pavé orange
= a³ + b³ + 3 × a² × b + 3 × a × b²
= a³ + b³ + 3ba² + 3ab²
c) a = 3 et b = -2
(a + b)³ = (3 - 2 )³ = 1³ = 1
a³ + b³ + 3ba² + 3ab² = 3³ + (-2)³ + 3 × 3² × (-2) + 3 × 3 × (-2)²
= 27 + (-8) + (-54) + 36 = 1
3) on développe
(a + b)³ = (a + b)²×(a + b)
= (a² + 2ab + b²)(a + b)
= a² × a + 2ab × a + b² × a + a² × b + 2ab × b + b² × b
= a³ + 2ba² + ab² + ba² + 2ab² + b³
= a³ + b³ + 3ba² + 3ab²
