help with the Quadratic formula?

4x^2 - 2x - 1 = 0

using the quadratic formula

Update:

i know what the qaudratic formula is and i have done it before but for some reason i keep getting this question wrong so could somebody please show the working out and explain to me??

any help would be greatley appreciated

Update 2:

answer in surd form please

5 Answers

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  • Jacko
    Lv 6
    9 years ago
    Favorite Answer

    Using the formula:- x= -b +/- square root of b^2 - 4ac all divided by 2a

    In this problem a=4, b=-2, c=-1

    So.... x= 2+square root of 4 - 4*-4 all divided by 8

    x=2+square root of 4- (-16) all divided by 8

    x=2+square root of 4+16/8

    x=2+square root of 20/8

    x=2+4.47/8

    x=6.47/8

    x=0.809

    You will now have to repeat this substituting the + sign after the 2, with a - sign to get the complete answer.

  • 9 years ago

    Using quadratic formula

    x = 1/4(1-sqrt(5)) or 1/4(1+sqrt(5))

  • Anonymous
    9 years ago

    Quadratic formula ... x= -b +/- √b)2 -4ac

    Divided by 2a

    X equals the opposite of b plus of minus square root of b square minus four a c divided by two a....

    Hope this helps

  • 9 years ago

    4x^2 - 2x - 1 = 0

    2x (2x-1) - 1 = 0

    (2x-1) (2x-1) = 0

    2x - 1 = 0

    2x = 1

    x = 1/2

    :)

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  • Mike G
    Lv 7
    9 years ago

    x = [2±sqrt(20)]/8

    x = 0.809 or -0.309

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