Mathématiques

Question

Bonjour, pouvez-vous m aider à résoudre les équations suivantes s'il vous plait :
2x + 10 = 0
2x + 10 = 5x - 2
2x - 3(x+2) = 6 + 5(x-4)
-1/7x + 1 = -x + 1/7

1 Réponse

  • Bonjour !

    2x + 10 = 0

    <=> (2x + 10) - 10 = (0) - 10

    <=> 2x = -10

    <=> (2x) / 2 = (-10) / 2

    <=> x = -5

    2x + 10 = 5x - 2

    <=> 2x + 10 = 5x - 2

    <=> 2x + 10 - 10 = 5x - 2 - 10

    <=> 2x = 5x - 12

    <=> 2x - 5x = 5x - 12 - 5x

    <=> -3x = -12

    <=> -3x / (-3) = -12 / (-3)

    <=> x = 4

    2x - 3(x+2) = 6 + 5(x-4)

    <=> 2x - 3x - 6 = 6 + 5x - 20

    <=> -x - 6 = 5x - 14

    <=> -x - 6 - 5x = 5x - 14 - 5x

    <=> -6x - 6 = -14

    <=> -6x - 6 + 6 = -14 + 6

    <=> -6x = -8

    <=> -6x / (-6) = -8 / (-6)

    <=> x = 8/6 = 4/3

    -1/7x + 1 = -x + 1/7

    <=> (-1/7x + 1) *  7 = (-x + 1/7) * 7

    <=> -x + 7 = -7x + 1

    <=> -x + 7 + 7x = -7x + 1 + 7x

    <=> 6x + 7 = 1

    <=> 6x + 7 - 7 = 1 - 7

    <=> 6x = -6

    <=> x = -6 / 6 = -1

    Voilà !

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