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31 January, 00:08

Use quadratic formula solve. 7x^2 - 28x - 7

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  1. 31 January, 03:55
    0
    x = 2 + sqrt (5) or x = 2 - sqrt (5)

    Step-by-step explanation using the quadratic formula:

    Solve for x over the real numbers:

    7 (x^2 - 4 x - 1) = 0

    Divide both sides by 7:

    x^2 - 4 x - 1 = 0

    Add 1 to both sides:

    x^2 - 4 x = 1

    Add 4 to both sides:

    x^2 - 4 x + 4 = 5

    Write the left hand side as a square:

    (x - 2) ^2 = 5

    Take the square root of both sides:

    x - 2 = sqrt (5) or x - 2 = - sqrt (5)

    Add 2 to both sides:

    x = 2 + sqrt (5) or x - 2 = - sqrt (5)

    Add 2 to both sides:

    Answer: x = 2 + sqrt (5) or x = 2 - sqrt (5)
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