Bonjour,
a) 45 ÷ 3 = 15
15 ÷ 3 = 5
donc 45 = 3 × 3 × 5 = 3² × 5
b) 34 ÷ 2 = 17
donc 34 = 2 × 17
c) 48 ÷ 2 = 24
24 ÷ 2 = 12
12 ÷ 2 = 6
6 ÷ 2 = 3
donc 48 = 2 × 2 × 2 × 2 × 3 = 2⁴ × 3
d) 56 ÷ 2 = 28
28 ÷ 2 = 14
14 ÷ 2 = 7
donc 56 = 2 × 2 × 2 × 7 = 2³ × 7
tu continues ?