7 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) merci ​