# Thread: Transposing an awkward formula

1. ## 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

2. ## 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.

3. ## Re: Transposing an awkward formula

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

4. ## 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

5. ## Re: Transposing an awkward formula

Originally Posted by ramalamafizzfaj
i dont understand how you jumped from x= L(L- 1)(500) to 500(L^2- L).
Do you understand the basic property of distributions: $\large x(x-1)=x^2-x~?$

6. ## Re: Transposing an awkward formula

no, thats why im here

7. ## Re: Transposing an awkward formula

Originally Posted by Plato
Do you understand the basic property of distributions: $\large x(x-1)=x^2-x~?$
Originally Posted by ramalamafizzfaj
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,