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9 May, 16:08

X² - 4x - 12=0

solve by completing the square

+2
Answers (1)
  1. 9 May, 16:35
    0
    x = - 2 0r x = 6

    Step-by-step explanation:

    from the question

    X² - 4x - 12=0

    solve by completing the square method

    we have;

    X² - 4x - 12=0

    X² - 4x = 12

    to make the left hand side a perfect square we add 4 to both sides.

    X² - 4x + 4 = 12 + 4

    X² - 4x + 4 = 16

    from left hand side X² - 4x + 4

    = (x - 2) * (x - 2)

    it can be simply expressed as

    (x-2) ²

    so since X² - 4x + 4 has been simplified to be (x-2) ²

    then,

    (x-2) ² = 16

    x - 2 = √ 16

    since square root has two values it can either be positive or negative

    so we have

    x = 2 + √16

    or

    x = 2 - √16

    therefore

    x = 2 + √16

    x = 2 + 4

    x = 6

    0r

    x = 2 - 4

    x = - 2
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