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    This is probably really stupid, but how do you solve solve y^3+3y-3=0?

    Thanks
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    (Original post by bertiejess)
    This is probably really stupid, but how do you solve solve y^3+3y-3=0?

    Thanks
    What level of mathematics do you currently have?

    If you are just looking for the real root, you could use a numerical method such as looking for a change of sign or using iteration.

    If you want to solve it exactly, you could notice that there is no y^2 term. This is called a depressed cubic and Google will show you how to deal with it.
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    (Original post by Mr M)
    What level of mathematics do you currently have?

    If you are just looking for the real root, you could use a numerical method such as looking for a change of sign or using iteration.

    If you want to solve it exactly, you could notice that there is no y^2 term. This is called a depressed cubic and Google will show you how to deal with it.
    this is in chapter 4 of C3
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    (Original post by bertiejess)
    this is in chapter 4 of C3
    Use Iteration. Chapter 4 is numerical methods if I remember correctly.
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    (Original post by Mr M)
    What level of mathematics do you currently have?

    If you are just looking for the real root, you could use a numerical method such as looking for a change of sign or using iteration.

    If you want to solve it exactly, you could notice that there is no y^2 term. This is called a depressed cubic and Google will show you how to deal with it.
    what is a depressed cubic Mr M?
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    (Original post by bertiejess)
    this is in chapter 4 of C3
    Ok

    f(y) = y^3 + 3y  - 3

    Find f(0) and f(1) - note there is a sign change so there is a root between 0 and 1.

    y^3 + 3y - 3 =0

    Rearrange into y = something.

    y = \frac{3-y^3}{3}

    Now use the right hand side as an iterative formula.

    Type into your calculator

    1 =

    (3 - ANS^3)/3 =

    Press = a lot

    This will converge to the real root
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    (Original post by Prokaryotic_crap)
    what is a depressed cubic Mr M?
    A really fed up polynomial?

    http://fermatslasttheorem.blogspot.c...sed-cubic.html
 
 
 
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