Mathématiques

Question

Calculer et donner le résultat sous la forme la plus simple.

A= 7/5 - 7/3 x 15/14 B= 8/5 - 3/4 : 9/8

C= 8/3 - 2/5 / 7/5

2 Réponse

  • A= 7/5 - 7/3 x 15/14
    A = 7/5 - 105/42
    A = 7 x 42 / 5 x 42 - 105 x 4 / 42 x 5
    A = 297/210 - 420/210
    A = - 123/210
    A = 3 x - 41 / 3 x 70
    A = - 41/70

    B= 8/5 - 3/4 : 9/8
    B = 8/5 - 3/4 x 8/9
    B = 8/5 - 24/36
    B = 8 x 36 / 5 x 36 - 24 x 5 / 36 x 5
    B = 288/180 - 120/180
    B = 168/180
    B = 12 x 14 / 12 x 15
    B = 14/15

    C= 8/3 - 2/5 / 7/5
    C = 8/3 - 2/5 x 5/7
    C = 8/3 - 10/35
    C = 8 x 35 / 3 x 35 - 10 x 3 / 35 x 3
    C = 280/105 - 30/105
    C = 250/105
    C = 5 x 50 / 5 x 21
    C = 50/21
  • A= 7/5 - 7/3 x 15/14
    a = 7/5 - 7/3 x 3*5/7x2
    a = 7/5 -5/2
    a = 14/10-25/10
    a = -11/10


    B= 8/5 - 3/4 : 9/8
    b = 8/5 -3/4 x8/9
    b =8/5 -3/4 x 4*2/3*3
    b = 8/5 -2/3
    b = 24/15 -10/15
    b= 14/15

    C= 8/3 - 2/5 / 7/5
    c = 8/3 -2/5x 5/7
    c = 8/3 -2/7
    c = 56/21 -6/21
    c = 50/21

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