Mathématiques

Question

Bonjour,

a. - 2/11 * 11/(-5) =
1) -5/2
2) 2/5
3) -2/5

b. (2/7 + 3/7) ÷ 1/5 =
1) 1/7
2) 25/7
3) 17/7

c. 5/2 - 2/3 ÷ 5/3 + 2/3
1) 3/3 ÷ 7/3
2) 5/3 - 2/5 + 2/3
3) 3/3 * 3/5 + 2/3

d. (2+3)/(4*7) s'écrit aussi...
1) (2 + 3) ÷ (4 * 7)
2) (2 + 3) ÷ 7(4 * 7)
3) 2 + 3 ÷ 4 * 7

1 Réponse

  • Bonjour,

    a. - 2/11 * 11/(-5) 
    = - 22/55
    = (11 x - 2) / (11 x 5)
    = - 2/5

    Réponse 3) -2/5

    b. (2/7 + 3/7) ÷ 1/5 
    = 5/7 x 5
    = 25/7

    Réponse 2) 25/7

    c. 5/2 - 2/3 ÷ 5/3 + 2/3
    = 5/2 - 2/3 x 3/5 + 2/3
    = 5/2 - 6/15 + 2/3
    = (5 x 15) / (2 x 15) - (6 x 2) / (15 x 2) + (2 x 10) / (3 x 10)
    = 75/30 - 12/30 + 20/30
    = 95/30 - 12/30
    = 83/30

    1) 3/3 ÷ 7/3
    = 3/3 x 3/7
    = 9/21
    = (3 x 3) / (3 x 7)
    = 3/7

    2) 5/3 - 2/5 + 2/3
    = (5 x 5) / (3 x 5) - (2 x 3) / (5 x 3) + (2 x 5) / (3 x 5)
    = 25/15 - 6/15 + 10/15
    = 35/15 - 6/15
    = 29/15

    3) 3/3 * 3/5 + 2/3
    = 9/15 + 2/3
    = 9/15 + (2 x 5) / (3 x 5)
    = 9/15 + 10/15
    = 19/15

    d. (2+3)/(4*7) s'écrit aussi...
    Réponse 1) (2 + 3) ÷ (4 * 7)

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