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Help please!!!!!!!!?

by Guest62812  |  earlier

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Solve 8x^3+1=0 using the sim of cubes formula

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  1. the sum on cubes formula factors this out to be (2x+1)(2x-1)(2x-1)=0

    Then set each of the equations in the parenthesis equal to zero.

    You come out with x= -1/2, 1/2


  2. Sorry but yahoo answers won't be in your exams hun x

  3. That made my brain hurt reading it.  Sorry I am of no service to ya dude.

  4. Well that would translate into 8x^3+1^3. That would be

    Formula is:

    Sum of Cubes  -  An expression of the form a^3 + b^3. The sum of two cubes factors into (a + b)(a^2 - ab + b^2).

    8+3( 8^2-8(1) +1^2)

    That would then be

    11(64-8+1)

    11(57)

    627

  5. (2x + 1) (4x^2 - 2x + 1) = 0

    2x + 1 = 0 and 4x^2 - 2x + 1 =0

    x = -1/2 and ...... use quadratic formula to find the rest (too lazy to do the rest)

  6. lol i hate math

  7. This is the sum of cubes formula: x3 + y3 = (x+y)(x2-xy+y2)

    Your equation can be rewritten as: (2x)^3 + 1^3 = 0

    Now you can apply the sum of cubes formula and get:

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

    Which means 2x + 1 = 0 and thus x = -1/2

    and also 4x^2 -2x + 1 = 0

    We solve the quadratic equation using quadratic formula:

    x1 = (2 + sqrt (4 - 16)) / 8 = (2 + sqrt(-12)) / 8

    x2 = (2 - sqrt(-12)) / 8

    So, the three roots are:

    -1/2

    (2 + sqrt(-12)) / 8

    (2 - sqrt(-12)) / 8

  8. i hate math

  9. huh ? explain it please o.o
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