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Thread: Transposing an awkward formula

  1. #1
    Newbie ramalamafizzfaj's Avatar
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    Transposing an awkward formula

    i have a formula for a videogame im trying to make, but ive forgotten more math than i ever knew. The formula is to show how many experience points are rerquired to advance to a given level. however, i would like to find out what level a character is based soley on their total XP. Please can you explain how this formula would be transposed to make L the subject


    x = l * (l-1) * 500
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  2. #2
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    Re: Transposing an awkward formula

    You say you want to make "L" the subject but there is no "L" in the equation! Did you mean "x= L(L-1)500"? (Small L, 'l' looks so much like I to me!) x= L(L- 1)(500)= 500(L^2- L) is equivalent to the [b]quadratic equation L^2- L= x/500. You can "complete the square" by adding 1/4 to both sides: L^2- L+ 1/4= (L- 1/2)^2= x/500+ 1/4= (x+ 125)/4. Now take the square root of both sides L- 1/2= +/- sqrt(x+ 125)/2.

    Finally, L= (1+/- sqrt(x+ 125))/2. That has two solutions, one positive and one negative.
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  3. #3
    Newbie ramalamafizzfaj's Avatar
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    Re: Transposing an awkward formula

    i dont understand how you jumped from x= L(L- 1)(500) to 500(L^2- L).

    can you explain more please
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    Re: Transposing an awkward formula

    Halls, I get "not quite" yours:

    L = [1 +- sqrt(1 + x/125)] / 2

    Example: if x = 10000, then L = 5 or -4
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    Re: Transposing an awkward formula

    Quote Originally Posted by ramalamafizzfaj View Post
    i dont understand how you jumped from x= L(L- 1)(500) to 500(L^2- L).
    can you explain more please
    Do you understand the basic property of distributions: $\large x(x-1)=x^2-x~?$
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    Newbie ramalamafizzfaj's Avatar
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    Re: Transposing an awkward formula

    no, thats why im here
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    Re: Transposing an awkward formula

    Quote Originally Posted by Plato View Post
    Do you understand the basic property of distributions: $\large x(x-1)=x^2-x~?$
    Quote Originally Posted by ramalamafizzfaj View Post
    no, thats why im here
    You need a sit down with a good tutor. That is a function that this forum does not do.
    Moreover, your basic misunderstandings are profound. You really need to start over with an course in basic algebra,
    Thanks from DenisB and ramalamafizzfaj
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