merci d'avance pour votre réponse ​

Bonjour !

A = 1/4 - 1/4 × 2/3

= 1/4 - 1×2/4×3

= 1/4 - 1×2/2×2×3

= 1/4 - 1/6

= 1×3/4×3 - 1×2/6×2

= 3/12 - 2/12

= 1/12

B = 2/3 + 1/2 / 17/9 - 1/3

= (2/3 + 1/2) ÷ (17/9 - 1/3)

= (2×2/3×2 + 1×3/2×3) ÷ (17/9 - 1×3/3×3)

= (4/6 + 3/6) ÷ (17/9 - 3/9)

= 7/6 ÷ 14/9

= 7/6 × 9/14

= 7×9/6×14

= 7×3×3/2×3×2×7

= 3/4