i want the way to solve this equation without using calculator to find value of x
x3 + ax2 + bx + c
$\displaystyle x^3+ax^2+bx+c =0 $
if you looking for formula to solve that in that form than.... hm... it's huge if those i assume constants a,b,c were numbers than could be shown how to reduce that equation so it could be solved easier
or you can use Horner scheme , but anyway you need one zero first
here is the problem link :
https://www.spoj.pl/problems/ROOTCIPH/
what is your idea
hm.....
try this if helps you : x^3+ax^2+bx+c=0 - Wolfram|Alpha
and here you are how to do cubic polynomial : Solving Cubic Equations
hm.... or because your are writing code for that, maybe it would be easier to test first zero, and than simplify cubic polynomial... as i recall you can use algorithm hm... can't remember right now but as soon as i do i'll write it here (long time passed since i have done any programming )