# Thread: Fifth equations.

1. ## Fifth equations.

Ok, I have been trying to solve this equation for almost a month now, even my math teacher don't know how to solve it, and it seem I'm not getting closer to an answer, so I decided to look for help on the internet.

Anyway, here is the equation I'm trying to solve (sorry if I posted this wrong, but it seems like it's worse to post a easy question in the hard question forum then the reverse),

(1200/x^1)+(1100/x^2)+(1000/x^3)+(900/x^4)+(800/x^5)=3098 (X=1.2)

3. ## Re: Fifth equations.

But there must be a way to solve it without a computer?

4. ## Re: Fifth equations.

if you put the 3098 on the left hand side, and multiply through by x^5, you get a quintic polynomial:

f(x) = 3098x^5 - 1200x^4 - 1100x^3 - 1000x^2 - 900x - 800.

there is no general formula for solving such a polynomial, and even with the few classes of polynomials for which formulae DO exist,they are typically horrendously ugly.

as Siron has indicated, numerical methods are your best bet. Newton's method would be one approach to try.