Calculer les produits suivants.
a.(-1) × (-2) × (-2) × (+1) × (-3)
b. (-4) × (-1) × (-1) × (+2) × (-3) × (-1)
c.(+5) × (-2) × (+2) × (+5) × (-1)
d. (-8) × (+2) × (+1) × (+1) × (-2) × (-2) × (-2)​