Bonjour,
b) 3/8 = 36/96 car 3 × 96 = 8 × 36
3/8 ≠ 2,4/5,6 car 3 × 5,6 ≠ 8 × 2,4
si 3/y = 5/7 alors 5y = 3×7 donc y = (3×7)/5 = 21/5
c) 12/16 + 10/15 = 3/4 + 2/3 = 9/12 + 8/12 = 17/12
42/25 - 5/4 = 168/100 - 125/100 = 43/100
120/48 = (5×24)/(2×24) = 5/2
d) 2 058 = 2 × 3 × 7 × 7 × 7
350 = 2 × 5 × 5 × 7
donc 2 058/350 = (2 × 3 × 7 × 7 × 7)/(2 × 5 × 5 × 7)
= (3 × 7 × 7)/(5 × 5)
= 147/25
