# Thread: Finding zeros of a polynominal that doesn't factor (and whose zeros are non-integers)

1. ## Finding zeros of a polynominal that doesn't factor (and whose zeros are non-integers)

I've got this here . . . x^3 +7x -1 = 0.

I know it equals x = 0.142 approx, but I found that out by graphing it. I'm stumped as to how to solve it algebraically.

Any help is much appreciated.

Thanks!

2. ## Re: Finding zeros of a polynominal that doesn't factor (and whose zeros are non-integ

Wikipedia has a pretty comprehensive article regarding how to solve a cubic algebraically.

Cubic function - Wikipedia, the free encyclopedia

3. ## Re: Finding zeros of a polynominal that doesn't factor (and whose zeros are non-integ

You should use a numerical method. Otherwise use the Cubic Formula if you really feel adventurous...

4. ## Re: Finding zeros of a polynominal that doesn't factor (and whose zeros are non-integ

Yea I'd go with what Prove it said above and that wiki article should help alot. if it helps at all your looking for 3 roots and two of them are complex roots.