Mathématiques

Question

Effectue les calculs suivants en détaillant les étapes :
c. 1/5--2/3
d. 4/18+5/27
e. 17/-24+(- 5/36)
f. 3/16--1/12
g. 8/-17-(- 1/15)
h. 2/5+-2/15- 7/12

1 Réponse

  • c. 1/5--2/3
    = 1/5 + 2/3
    = 1 x 3 / 5 x 3 + 2 x 5 / 3 x 5
    = 3/15 + 10/15
    = 13/15

    d. 4/18+5/27
    = 4 x 27 / 18 x 27 + 5 x 18 / 27 x 18
    = 108/486 + 90/486
    = 198/486
    = 18 x 11 / 18 x 27
    = 11/27

    e. 17/-24+(- 5/36)
    = - 17/24 - 5/36
    = - 17 x 3 / 24 x 3 - 5 x 2 / 36 x 2
    = - 51/72 - 10/72
    = - 61/72

    f. 3/16--1/12
    = 3/16 + 1/12
    = 3 x 3 / 16 x 3 + 1 x 4 / 12 x 4
    = 9/48 + 4/48
    = 13/48

    g. 8/-17-(- 1/15)
    = - 8/17 + 1/15
    = - 8 x 15 / 17 x 15 + 1 x 17 / 15 x 17
    = - 120/255 + 17/255
    = - 103/255

    h. 2/5+-2/15- 7/12
    = 2/5 - 2/15 - 7/12
    = 2 x 12 / 5 x 12 - 2 x 4 / 15 x 4 - 7 x 5 / 12 x 5
    = 24/60 - 8/60 - 35/60
    = - 19/60

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