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Alpha and Beta Rules

  • 30-05-2012 8:16pm
    #1
    GarIT
    Registered Users, Registered Users 2 Posts: 8,671 ✭✭✭


    Are any of the rules for roots in the log tables? I haven't been able to see them anywhere.


Comments

  • #2
    reznov
    Registered Users, Registered Users 2 Posts: 921 ✭✭✭reznov


    Nope. But there are only two to learn anyway.


  • #3
    ChemHickey
    Closed Accounts Posts: 3,479 ✭✭✭ChemHickey


    reznov wrote: »
    Nope. But there are only two to learn anyway.

    One, if you just use the algebra alpha^3 + beta^3.


  • #4
    ChemHickey
    Closed Accounts Posts: 3,479 ✭✭✭ChemHickey


    ChemHickey wrote: »
    reznov wrote: »
    Nope. But there are only two to learn anyway.

    One, if you just use the algebra alpha^3 + beta^3.

    To clarify, that's (a + b)(a^2 - ab + b^2) where a is alpha and b is beta.


  • #5
    reznov
    Registered Users, Registered Users 2 Posts: 921 ✭✭✭reznov


    ChemHickey wrote: »
    To clarify, that's (a + b)(a^2 - ab + b^2) where a is alpha and b is beta.

    Nah. There's two:
    a + b = -b/a and ab = c/a

    All you need really. There reset are identities which can be derived with basic algebra.


  • #6
    ChemHickey
    Closed Accounts Posts: 3,479 ✭✭✭ChemHickey


    reznov wrote: »
    ChemHickey wrote: »
    To clarify, that's (a + b)(a^2 - ab + b^2) where a is alpha and b is beta.

    Nah. There's two:
    a + b = -b/a and ab = c/a

    All you need really. There reset are identities which can be derived with basic algebra.

    Oh those, you don't even need to know the formula if you know that x^2-(sum of roots)+product of roots. **

    If there is a number in front of the x^2 just. divide across. eg. ex^2-gx+k would be

    x^2-(g/e)x (k/e)

    and then just equate with ** from above.


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  • #7
    reznov
    Registered Users, Registered Users 2 Posts: 921 ✭✭✭reznov


    ChemHickey wrote: »
    Oh those, you don't even need to know the formula if you know that x^2-(sum of roots)+product of roots. **

    If there is a number in front of the x^2 just. divide across. eg. ex^2-gx+k would be

    x^2-(g/e)x (k/e)

    and then just equate with ** from above.

    Yes I know from what they're derived. I mean if you didn't know, that's all you need to remember. Identites can be derived just as easily.


  • #8
    ChemHickey
    Closed Accounts Posts: 3,479 ✭✭✭ChemHickey


    reznov wrote: »
    ChemHickey wrote: »
    Oh those, you don't even need to know the formula if you know that x^2-(sum of roots)+product of roots. **

    If there is a number in front of the x^2 just. divide across. eg. ex^2-gx+k would be

    x^2-(g/e)x (k/e)

    and then just equate with ** from above.

    Yes I know from what they're derived. I mean if you didn't know, that's all you need to remember. Identites can be derived just as easily.

    Yep, as do I. it's for those who don't.


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