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Math Help - Solving equation

  1. #1
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    Solving equation

    Hi could someone please help me solve the following eqation:

    4(1+r)^4-2(1+r)^2-3=0

    I Know if it was a qudratic, just use the formula, but how does one solve for degree 4.

    Thanks
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  2. #2
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    Quote Originally Posted by 1234567 View Post
    Hi could someone please help me solve the following eqation:

    4(1+r)^4-2(1+r)^2-3=0

    I Know if it was a qudratic, just use the formula, but how does one solve for degree 4.

    Thanks
    let t = (1+r)^2

    4t^2 - 2t - 3 = 0

    use the quadratic formula and solve for t (remember that t will have to be > 0 ) ... then solve for r.
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  3. #3
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    Quote Originally Posted by skeeter View Post
    let t = (1+r)^2

    4t^2 - 2t - 3 = 0

    use the quadratic formula and solve for t (remember that t will have to be > 0 ) ... then solve for r.
    Thanks for the hint, i should manage to solve the problem now.
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  4. #4
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    Quote Originally Posted by 1234567 View Post
    Hi could someone please help me solve the following eqation:

    4(1+r)^4-2(1+r)^2-3=0

    I Know if it was a qudratic, just use the formula, but how does one solve for degree 4.

    Thanks
    You could substitute

    x=(1+r)^2

    4x^2-2x-3=0

    Now use the quadratic formula, realising that x is a square, hence positive,
    so you only need to take one solution for x.

    Rearranging your solution for x will achieve the 2 solutions for r.
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  5. #5
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    Quote Originally Posted by Archie Meade View Post
    You could substitute

    x=(1+r)^2

    4x^2-2x-3=0

    Now use the quadratic formula, realising that x is a square, hence positive,
    so you only need to take one solution for x.

    Rearranging your solution for x will achieve the 2 solutions for r.
    Why are you assuming only real solutions are wanted?
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