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How to find roots of a cubic equation?

I'm facing problem in which finding of roots of quadratic equation is required. I know one method to find roots that find one root by guessing and then factorise the cubic into a linear and quadratic and then apply quadratic formula. But this only works when roots are guessable i.e. 0,±1,±2. But this do not works when roots are fractional or large integers. So I want to know is there any other way to find roots of a cubic equation? Any useful answer will be appreciated by me. Thank You!!!

sgrmshrsm7
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    You can always use Cardano's formula https://www.encyclopediaofmath.org/index.php/Cardano_formula – clark Apr 24 '17 at 06:12
  • @clark in cardano formula there is only one expression for x so it will give only one root. What about other two roots? Sir, correct me if I'm telling something wrong. – sgrmshrsm7 Apr 24 '17 at 13:36
  • If you have one of the roots, you can factorize your polynomial into a degree 1 and a degree 2 factor. I'm sure you can solve the degree 2 polynomlial equations already. – Raskolnikov Nov 02 '17 at 18:49

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