



 
Faiz, Are you sure you have this question stated correctly? There is a procedure for solving cubics similar to the general quadratic expression for quadratics. It's called Cardano's method. This method or something equivalent is what Mathematica uses to solve cubics. When we tried Mathematica with your equation x^{3}  6x^{2} + 3x + 5 = 0 using the Quick Math site we got the following Janice and Harley  


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