Mathématiques

Question

Bonjour, pouvez vous m'aider svp ? 

 2/3×9/5-1/4

(4/5-2)×(3/4-2/3)

(2/5+1/3)÷2/3

16/15÷2/9-2/3

2/13-5/13÷10/16 


Merci d'avance.

1 Réponse

  • 2/3 × 9/5 - 1/4
    = 18/15 - 1/4
    = 18 x 4 / 15 x 4 - 1 x 15 / 4 x 15
    = 72/60 - 15/60
    = 57/60
    = 3 x 19 / 3 x 20
    = 19/20

    (4/5 - 2) × (3/4 - 2/3)
    = (4/5 - 2 x 5 / 1 x 5) x (3 x 3 / 4 x 3 - 2 x 4 / 3 x 4)
    = (4/5 - 10/5) x (9/12 - 8/12)
    = - 6/5 x 1/12
    = - 6/60
    = 6 x - 1 / 6 x 10
    = - 1/10

    (2/5 + 1/3) ÷ 2/3
    = (2 x 3 / 5 x 3 + 1 x 5 / 3 x 5) : 2/3
    = (6/15 + 5/15) : 2/3
    = 11/15 x 3/2
    = 33/30
    = 3 x 11 / 3 x 10
    = 11/10

    16/15 ÷ 2/9 - 2/3
    = 16/15 x 9/2 - 2/3
    = 144/30 - 2/3
    = 144/30 - 2 x 10 / 3 x 10
    = 144/30 - 20/30
    = 124/30
    = 2 x 62 / 2 x 15
    = 62/15

    2/13 - 5/13 ÷ 10/16
    = 2/13 - 5/13 x 16/10
    = 2/13 - 80/130
    = 2 x 10 / 13 x 10 - 80/130
    = 20/130 - 80/130
    = 60/130
    = 10 x 6 / 10 x 13
    = 6/13

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